Updated 12:08 a.m.

Veteran Chicago Ald. Pat O’Connor lost the North Side City Council seat he’s held for nearly four decades, falling to political newcomer Andre Vasquez in Tuesday’s city runoff election.

Mayor Rahm Emanuel’s floor leader, O’Connor ranked as one of the City Council’s most powerful members. He had the second-longest tenure and chaired the Finance Committee, a post he assumed in the backdraft of the federal corruption probe that ensnared 14th Ward Ald. Edward Burke.

But while Burke survived his re-election bid in February, O’Connor’s defeat was decisive. With 100 percent of precincts reporting, Vasquez led O’Connor by a 54 percent to 46 percent margin — a spread of more than 1,000 votes out of more than 13,000 cast.

“The machine’s crumbling,” Vasquez said. “You talk to people in the city, and for a long time, they either tried to ignore or accept the fact that it’s corrupt, silently wanting better.”

“I think this is a time we’re seeing leaders step up,” he said.

O’Connor, meanwhile, was reflective late Tuesday when reached by WBEZ.

“I’ve had a great run, and every run doesn’t last forever, and I didn’t expect it would,” he said. “But I’m very happy with the things we’ve been able to accomplish.”

Vasquez forced O’Connor, who has held the seat for 36 years, into a runoff after the Feb. 26 election. In a crowded five-way race, Vasquez took 20 percent of the vote while O’Connor came away with just 33 percent — far shy of the majority he would have needed to win the race outright.

The 40th Ward covers parts of Lincoln Square, Budlong Woods and Andersonville. The area has changed since 1983 when O’Connor first took office as a 28-year-old. Younger voters and more immigrant families have moved into the area. That population shift seems to have favored his challenger, Vasquez.

The fact that O’Connor was forced into a runoff election could speak to strong anti-establishment sentiment among Chicago voters. As the unofficial floor leader for both Mayors Richard M. Daley and Rahm Emanuel, O’Connor was tasked with pushing the fifth floor’s legislative agenda.

But O’Connor’s challengers cast that role in a negative light and called out his support of a property tax hike, new water and sewer fees and a monthly garbage fee over the last term. All were needed to cover growing pension payments and largely fell on the backs of single-family homeowners, one of the largest constituencies in his ward.

Vasquez, 39, is senior manager for a utility company. He volunteered for Bernie Sanders’ 2016 presidential campaign, and he’s the chair for the north chapter of Reclaim Chicago, a progressive PAC.

His life before that garnered some controversy during the campaign. In his 20s, Vasquez had a hip-hop career under the stage name Prime. In the weeks leading up to Tuesday’s runoff election, O’Connor supporters uncovered lyrics and social media comments Vasquez made years ago that were homophobic and misogynistic.

Vasquez apologized, saying there was no excuse for his behavior and that he is no longer the same person who made the offensive comments.

But those comments again were brought up last month during a candidate forum ahead of the runoff.

“My record gets brought up all the time. I think his record is fair game,” O’Connor said at the forum. “You should know those things had occurred. When my children were young, they used to apologize sometimes when they did something wrong. Mr. Vazquez’s apology was so he could run for office.”

Vasquez fired back, recalling O’Connor’s role as a member of the so-called “Vrdolyak 29.” During the racially charged council wars of the 1980s, then-Ald. Edward “Fast Eddie” Vrdolyak led a mostly white group of aldermen in trying to obstruct Mayor Harold Washington, the city’s first black mayor.

At the forum, Vasquez also noted a comment O’Connor made to then-candidate Ugo Okere, who is of Nigerian descent, during a February forum. O’Connor had criticized Okere’s campaign flyers for talking about “building Nigerian power in Chicago.”

“Two forums ago, [O’Connor] actually used racially divisive language against another candidate, and we have never heard an apology for that,” Vasquez said.