This past summer, Edward I. Koch, a Democrat, made headlines by noisily endorsing Republican Bob Turner in a special election to fill the congressional seat of disgraced Tweeter Anthony Weiner. The former mayor explained that he'd decided to rally Jewish voters in Brooklyn and Queens to chastise President Obama for his Israel policy. Koch's outsize role in Turner's surprise victory made for big political news and led to speculation that Obama could be facing trouble in his reelection bid.

The episode was unusual, but unusual has always been de rigueur for Koch, a three-term mayor and a constant post-mayoral presence in New York City. For one thing, Koch has long described himself as a "liberal with sanity" in a city that consistently tilts left. Further, Koch's personality and ego have always been larger than life, and long before the era of 24-hour news, the mayor found imaginative ways to keep himself in the spotlight. So while the role he played in the Turner election was eye-catching, it wasn't surprising when you considered his eventful, iconoclastic career.

Ed Koch was born in the Bronx in 1924 to Polish Jewish immigrant parents. After completing his law degree at NYU and beginning his legal career, he moved into an apartment in Greenwich Village, where he became involved in local Democratic politics. In 1963, he ran for Greenwich Village district leader as a reform Democrat and won, beating the powerful machine pol Carmine De Sapio. Koch's willingness to run against the local Democratic Party machine was an early sign of his independence: for this Democrat, party loyalty wasn't the ultimate virtue.

In 1968, Koch ran for Congress and proved a tireless politicker. One month before the election, his opponent, Whitney North Seymour, Jr., saw him asking for votes outside a subway station, struck up a conversation, and asked how long he had been doing that kind of campaigning. "Oh, about a year," Koch replied. The "look on Seymour's face," Koch wrote in his autobiography, Mayor, meant that Seymour knew that the man with two names was going to beat the man with four names.

At first, there weren't many indications that Koch would be anything but a run-of-the-mill Democratic congressman. As he remembered in a 2007 article for the New York Press, "I was just a plain liberal." But he made a telling deviation from convention in 1972, when residents of Forest Hills in Queens were protesting the planned development of three 24-story buildings that would house 4,500 residents on public assistance. The protests seemed to pit the Jewish residents of Forest Hills against the African-American community. Koch sided with the protesters and called for a reduction in the size of the developments.

Koch soon displayed another hallmark: his ability to feud. In 1976, when the large-hatted New York liberal Bella Abzug was running for Senate, a leftist group with Abzug's name on the masthead sent 76 senators a letter that opposed the sale of jets to Israel. Koch wrote a letter that supported the sale and excoriated those who opposed it. He then placed both letters in the Congressional Record and, using the congressional franking privilege, mailed them to "every Jewish group I knew," he wrote in Mayor. Abzug started getting calls from Jewish leaders blasting her about the letter, prompting her to ask Koch, "What are you trying to do, destroy me?" Unsurprisingly, she ended up losing the race. Koch's most famous comment about Abzug was in response to reporters who asked why she'd failed to win her own district in a 1972 congressional primary. Koch's answer: "Her neighbors know her."

New York in the seventies was plagued with a fiscal collapse, racial tensions, high crime, blackouts, and a terrifying serial killer, David "Son of Sam" Berkowitz. The city was also saddled with a mayor, Abe Beame, who didn't seem up to the task of governing, which led Koch to consider running against him. The New York Times wrote in Beame's obituary that "the four years of his mayoralty were among the most troubled in city history." As Koch recalled, Beame was "in over his head," so much so that he used to ask comptroller Harrison Goldin after important developments, "Would you explain to me what happened?" One night, Jonathan Mahler relates in his book Ladies and Gentlemen, the Bronx Is Burning, the hapless Beame was alerted to the good news that homicide detectives had captured Berkowitz. Beame rushed down to police headquarters to share in the NYPD's glory—only to mistake the killer for a plainclothes detective and shake his manacled hand before the cameras. Beame's press secretary, Sidney Frigand, referred to the incident as "the photo op from hell."

Koch had thrown his hat into the mayoral ring once before, in 1973, but quickly pulled back. In 1977, the timing was far better. Unsurprisingly, other politicians saw Beame's weakness as well; in addition to Beame and Koch, the Democratic primary included Abzug and Mario Cuomo, the establishment choice. At one point, New York governor Hugh Carey and former mayor Robert Wagner asked Koch to step aside in favor of Cuomo. Koch's defiant reply: "You're looking at the guy who is going to win."

Koch's political savvy and seemingly limitless energy allowed him to finish in the winner's circle in the first round of the bruising primary and then to defeat Cuomo in a runoff. The effects of the runoff were felt in New York politics for decades, as Koch held Cuomo responsible for an ugly antigay slogan, referring to rumors about Koch's sexual orientation, that bubbled up among Cuomo supporters. The acrimony between the two men continued through the rest of their political careers.

In January 1978, Koch became mayor of New York, but that prize was of questionable value in such a troubled city. Koch remembered how slim his prospects of success were when I spoke with him last year: "Everyone I knew said, 'It's hopeless, and you are going to be the guy responsible for taking us into bankruptcy.' " Undeterred, he went about addressing New York's problems with his characteristic bluntness and humor.

One of his keenest weapons was his cleverness in dealing with the press. In Ed Koch and the Rebuilding of New York, Jonathan Soffer writes that Koch talked to reporters "incessantly—sometimes even in the men's room." Though the authors of another book about the mayor, I, Koch, are reporters and Koch critics, they acknowledge that "one reason Koch did so well with the press was that most reporters liked him." He was also good copy. "He spoke words sharply, and the press loved hearing that," journalist Ken Auletta remembered in 2005.

Koch was particularly good on TV, thanks to his plainspoken style and the advice of media strategist David Garth. As the I, Koch authors observed, "Under Garth's tutelage, Koch made [television] work for him like no politician the city has ever seen." He also learned how to use interviews to his advantage. He had a knack for speaking "right past the reporter, straight to the audience, . . . [and he] got better and better at it, much to the chagrin of the TV reporters who felt themselves little more than stage props for his antics."

Eventually, Koch became a bona fide media star. In an era before Google, Twitter, Facebook, and even 24-hour cable news, he managed to find a way to inject himself into the homes of New Yorkers on a daily basis. "New Yorkers who listened to the radio could expect to hear Ed Koch's voice," write the authors of I, Koch. "When they picked up newspapers, there he was. When they turned on the evening news, he was often the star." One of those authors, Michael Goodwin of the Daily News, jokes that "Mayor Koch was in your face for so long that a whole generation of children grew up thinking 'Mayor' was his first name." Koch became part of the national scene as well. As People put it, "His frequent appearances in film (The Muppets Take Manhattan) and on national television, including Saturday Night Live (five times) and The Tonight Show (three times), have made him America's best-known mayor." He graced the cover of Time in 1981. There was even a Broadway show about him, Mayor, which ran for 250 performances.

Of course, some of the media blitz happened because Koch's considerable self-regard made him so interesting. Koch himself recognized the fact of his egotism: when telling me about his four biggest accomplishments, he prefaced them by noting that he was "putting humility aside, which is easy for me." According to an anonymous source cited in I, Koch, the middle initial in "Edward I. Koch" stood for the mayor's "favorite personal pronoun."

But ego doesn't fully explain Koch's appeal. If he'd simply been selling himself in those TV appearances, New Yorkers would have seen through it. Rather, Koch conflated his mayoral success with New York's success. As the New York Times wrote in 1989, "Edward Irving Koch has personalized the mayoralty with such delight that the line between Mayor and city blurred during the 12 years he has led New York." What appealed to New Yorkers was the sense that Koch was out there selling the city, both to itself and to the rest of the world. The I, Koch team writes that Koch was "New York's tireless, most optimistic cheerleader. No matter what the problem, the city was wonderful." According to the late New York senator Daniel Patrick Moynihan, Koch had "given New York City back its morale." Or, as Koch himself put it: "I gave the people back their spirit."

Koch's charisma could go only so far, though. In his first term, recognizing the seriousness of New York's fiscal situation, Koch put aside his liberalism and embraced a program of austerity, management reforms, and limited handouts from Washington and Albany. According to Soffer, "Koch's tireless and personal lobbying campaign for federal loan guarantees, along with other management reforms, led to a balanced budget by 1981—quite simply the greatest turnaround accomplished by any New York mayor in the 20th century, including Fiorello La Guardia."

As Koch tells it, his decision to balance the budget a year earlier than anticipated—a decision that made the turnaround seem all the more impressive—was "serendipitous." A Wall Street Journal reporter had asked deputy mayor Nat Leventhal what it would take to balance the budget a year ahead of schedule. Leventhal mentioned the query to Koch, who liked the idea and brought it up at a staff meeting. After an hour of discussion, Koch asked for a show of hands: Who wanted to proceed with the accelerated plan? The proposal narrowly failed, but aide Jim Brigham noted that many of those voting against it were lower-ranking staff. Koch held a second vote, this time including just commissioners and deputy mayors, and the idea narrowly passed.

The fiscal crises faced by many municipalities, states, and countries today make Koch's example worth returning to. The New York Times noted that "before [Koch's] first term was out, the city had regained access to the credit markets and was borrowing again on its own." The Times praised both the symbolic and the substantive aspects of this achievement: "With the facility of a stand-up comic and the sternness of an accountant, Ed Koch got New Yorkers to accept difficult and unpopular fiscal decisions."

Koch was also determined to change the nineteenth-century way that New York's government operated. According to the Times, he "made a fractious bureaucracy for the first time conform to 'GAAP'—generally accepted accounting principles." Soffer observes that Koch initiated "on-time payment of bills in a city that had kept its past-due bills in shoe boxes." Koch tells me that he's particularly proud of making the judicial selection process more open: instead of simply choosing judges who would then be reviewed to see if they were qualified, he asked an outside committee to select three candidates for each seat and then picked one of the three.

Koch encouraged a building spree that helped New York in several ways. According to former deputy mayor Robert Esnard, Koch "would joke that the taller the building, the more taxes there are." But the buildings helped give New York its swagger as well as its economic footing. And they attracted the financial, insurance, and real-estate industries that Koch felt New York needed.

In 1978, Koch helped make the career of the young Donald Trump, ending years of behind-the-scenes wrangling under previous mayors and announcing, along with Governor Hugh Carey, the development of a $257 million convention center in the West 30s. Trump characteristically hyped the project as "perhaps the most significant economic decision made in New York City since the building of the United Nations." Other Trump projects completed during Koch's mayoralty included the glitzy Trump Tower and the refurbishment of Central Park's Wollman Skating Rink.

A characteristic example of the Koch-era building boom was the AT&T building, now known as the Sony Building. Completed in 1984, it was "the most significant postmodern structure anywhere," according to Dirk Stichweh, author of New York Skyscrapers. As John Mollenkopf notes in A Phoenix in the Ashes: The Rise and Fall of the Koch Coalition in New York City Politics, AT&T benefited from a $42 million tax abatement for the project, under a tax-incentive program that predated Koch but that his administration "warmly embraced." Tax incentives were only one of the ways in which Koch encouraged commercial development. Rather than formulating a broader development policy, Mollenkopf explains, the administration expedited particular projects, which benefited from "extensive public financial support, including special tax exemptions, zoning bonuses, city loans and grants, capital improvements to the sites, and in some cases leases from city agencies as tenants."

Koch was particularly skilled at maneuvering inside Washington. In Mayor, he describes the Carter administration's increasingly desperate attempts to secure his backing for the reelection campaign in 1980. Koch knew that he needed federal help to deal with New York's fiscal challenges, but he also recognized a doomed political effort when he saw one. He supported Carter against Ted Kennedy in the Democratic primaries—a relatively easy decision—but only nominally backed Carter in the general election against Ronald Reagan. At the same time, he was relentless in his criticism of the Carter administration's tough stance toward Israel and was gracious in his treatment of Reagan during his campaign visit to New York. At the meeting, which the Carter folks grumbled about, Reagan granted important pledges of support to New York, which Koch would later ensure that Reagan honored as president.

A key moment of Koch's first term was the 1980 transit strike, in which he took a hard line against the transit union. In general, he wasn't averse to wage hikes; in fact, after the early eighties, he would rapidly increase all components of city spending, from compensation to building projects, notes Mollenkopf. But when the transit union walked away from the table, Koch quickly blamed the strike on the union and put an emergency transit plan into effect. He insisted that the strikers be penalized, as the Taylor Law, which forbade public-sector workers from striking, dictated. After previous strikes, the fines had generally been forgiven. He famously walked the short distance from his office to the Brooklyn Bridge to greet New Yorkers traipsing into Manhattan. Though the wage settlement that ended the strike was higher than Koch would have liked, he "declared victory," as Soffer writes, and had good reason to do so.

Koch's various efforts—political, rhetorical, and substantive—were rewarded with tremendous popularity. When he ran for reelection in 1981, he did so as both a Democrat and a Republican and garnered 75 percent of the vote, winning every assembly district. Koch had reason to crow, and, of course, he did: "It was the biggest majority a New York City mayor has ever received in modern times." Four years later, Koch won a third term with an even larger percentage of the vote.

Koch was a city boy through and through, a man who wore Brooks Brothers suits, loved his Greenwich Village apartment, and was addicted to the New York Times (once, on a European trip, he arranged to have the paper shipped to him). He used to say that he didn't worry about offending other politicians, since he never wanted to be anything except mayor: "I'm never going to need anybody's endorsement because I'm never running for anything—not Senator, not Governor, Vice President or President."

Such remarks hurt him when he decided, during his second term, to enter the Democratic primary for governor, running against Mario Cuomo. Upstate voters also weren't pleased with his observation that rural life consisted of "wasting time in a pickup truck . . . to drive 20 miles to buy a gingham dress or a Sears Roebuck suit." Koch's very popularity in New York City worked against him in the gubernatorial race: the Cuomo campaign pointed out that if their candidate won the primary, Gotham voters could keep their beloved mayor. Koch lost the primary and returned to his work, recommitted to his earlier, and probably wiser, view that mayor was his highest aspiration.

Koch's administration had failures, too, especially in his second and third terms. His best-known misstep was his inability to prevent the corruption scandals that plagued his third term, which involved embarrassing revelations of kickbacks, graft, and bribery on the part of Bronx politician Stanley Friedman and Queens borough president Donald Manes. Nearly all analysts, journalists, historians, and contemporaries agree that Koch himself was never in any way corrupt. But either Koch was naive about the goings-on or he had made too many deals with the Democratic machine to manage people like Friedman, who was an ally of the powerful boss Meade Esposito. As Soffer puts it, "his relationships with the regular Democratic leaders had become too close, and he should have been more cautious."

Koch recognized the impact of the scandals on his reputation and suspects that he fell into a state of clinical depression in their aftermath. He refused to see a psychiatrist but took solace in the nearly universal judgment of his own individual innocence, which then–United States Attorney for the Southern District of New York Rudy Giuliani, who investigated the scandals, acknowledged. Koch emerged from his depression, he told New York years later, after his close friend Cardinal John O'Connor called and assured him, "Everybody knows you're an honest man."

Koch also proved largely unsuccessful with respect to public safety. The homicide rate, in particular—citywide murders hit a record high of 2,245 in 1990, shortly after he left office—was a stain on his record, even though one of its causes, the 1980s crack epidemic, wasn't his fault. Koch did initiate some crime reforms that later bore fruit, such as Henry Stern's plan to improve Central Park security after the infamous rape of a Central Park jogger in 1989: felonies in the park dropped from 537 in 1988 to 368 in 1990 to 97 in 2008. Koch's rhetoric on crime was important, too. As Koch wrote (with Daniel Paisner) in the autobiographical Citizen Koch, he developed a reputation as a politician "who was not afraid to speak out about crime and its root causes and was willing to defend himself against the unfair charges of racism that such honesty evoked." His honesty didn't solve the crime problem—far from it—but it did help set the stage for the Giuliani-era policies that would later make New York safe.

Unfortunately for Koch, his disregard for being accused of racism meant that he didn't hesitate to close Sydenham Hospital in Harlem, which he later called one of his biggest political mistakes. Even though, as Koch recalled in an interview for the website Big Think, "every mayor before me, and myself included, was told by all the experts that a hospital located in Harlem which did not provide very good medical care should be closed," the shuttering caused a huge backlash for which he was unprepared. Soffer writes that Harlem congressman Charles Rangel "compared Koch to Bull Connor in the course of the Sydenham closing," which created an "indelible" image. According to Soffer, though, the Sydenham closing was just a symptom of a larger problem: Koch's "most profound error was failing to build trust and working alliances with black leaders and communities in the city." These problems with the black community ended up costing Koch dearly in the 1989 Democratic mayoral primary, as blacks turned out in droves to back one of their own—David Dinkins, who won the nomination and the mayoralty.

But it wasn't just Koch's problems with the African-American community that hurt him. Koch's style as a politician—his familiarity with reporters, his outspokenness, his brashness—became less of an asset over time. The frustrations of his second and third terms, and especially the high murder rate and the corruption scandals, made it harder for him to pull off the cheerleader role. In addition, Koch's pro-development, anti-racial-handouts, tough-on-unions approach had long been unpopular with some of the New York Democratic Party's stalwart constituencies: public-sector unions, race baiters, and social advocates. Within these groups, a liberal with sanity found no home.

Since serving as mayor, Koch has hosted radio and TV shows, written newspaper columns and movie reviews, and been a partner at a law firm. He has written at least a dozen books since leaving office, and every Saturday, he meets some of the top staff from his administration for lunch.

He also occasionally gets involved in politics. He remains a Democrat and a liberal, but occasionally his actions will surprise. In 2004, he supported and campaigned for the reelection effort of George W. Bush, even though, he said, "I don't agree with him on a single domestic issue." In 2008, he was back in the Democratic fold, supporting Obama for president. Though he has now endorsed Obama for reelection, he has also been an occasional thorn in the president's side—backing Turner in the Weiner special election; criticizing Obama's chilly relationship with Israel; and publicly hoping that current New York mayor Michael Bloomberg enters the presidential race as an independent. Because he is unreliable as a Democrat, he has relatively little say within New York City's Democratic Party.

Koch became mayor at New York's nadir and, using his signature mixture of media smarts, pluck, and sheer determination, managed to bring the city back from the brink. It surely doesn't detract from Rudy Giuliani's deeply impressive reign, which began in 1994, to suggest that Koch deserves credit for getting Gotham to the point where Giuliani could tackle the job. The renaming of the Queensboro Bridge after Koch in 2010 may be an imperfect way to honor a man who once said that going to Queens gave him "nosebleeds." But it's clear that Koch deserves a place of honor in the pantheon of New York's most successful mayors.