Pressley finishes first: The councillor addressed a cheering crowd outside her Dorchester Ave. headquarters on Tuesday night. Photo by Mike DeehanBy 9:45 p.m. Tuesday, the city’s political conventional wisdom had been upended: Ayanna S. Pressley, widely considered before the voting as the most vulnerable at-large councillor, based on her fourth place finish in 2009, easily vaulted to the top of the at-large ticket with a 2,041-vote margin over second-place finisher Felix G. Arroyo.

And Michael F. Flaherty, a former president of the City Council who was viewed by most as having a lock on reclaiming a seat based on his high name recognition and an expected high turnout in South Boston, finished out of the running in fifth place, 922 votes behind incumbent Council President Stephen J. Murphy.

After the polls had closed and the final results had trickled in, hundreds of supporters filled the Dorchester Avenue sidewalk outside of Pressley’s campaign headquarters in Peabody Square where their candidate stood atop a chair to address the crowd, which included Gov. Deval Patrick and a multitude of local elected officials.

“Anybody who doubts that you have all the power you need to make all the change you want, come and look at the outcome of this election,” Patrick said.

“Our whole city is reflected on this sidewalk,” said Pressley, adding “I cannot believe what we accomplished tonight as a city.”

Several supporters saw that accomplishment as a victory over politics-as-usual in Boston. “It’s a new day in Boston,” said veteran campaign aide Jim Spencer, who worked on former City Councillor At-Large Sam Yoon’s mayoral campaign in 2009.

Pressley, who took first place with 37,506 votes, said she had 500 supporters on the streets on Tuesday, pulling voters for her. She had heavy support from fellow City Councillor At-Large John Connolly and the political operation of Mayor Thomas Menino, as well as a barrage of news articles and opinion pieces highlighting the assumption of her vulnerability.

Pressley, who gathered 37,506 votes, said she had 500 supporters on the streets on Tuesday pulling voters for her. She had heavy backing from fellow City Councillor At-Large John Connolly and from the political operation of Mayor Thomas Menino and other elected officials across the city.

In the end, voters kept the at-large team in place, rejecting the challenges of three other candidates. Arroyo, the second Latino to serve on the council and like Pressley, finishing up his first term, gained 35,465 votes; Connolly, who topped the ticket in 2009, slid into third place, with 32,803 votes; and Murphy earned 26,712 votes in edging out Flaherty.

“I’m just happy to be reelected. If I couldn’t top the ticket, I would want it to be Ayanna,” said Connolly who raised $10,000 for Pressley, appeared with her at over 30 events, and spent thousands of dollars on direct mail and letters to voters.

The sixth and seventh place finishers were far behind, with Will Dorcena, a Hyde Park activist, picking up 8,736 votes, or 5 percent. Sean Ryan, a Jamaica Plain resident who has run for City Council in the past, received 7,373 votes, or 4.21 percent.

Competition for the four at-large seats had been fierce throughout the year. Flaherty’s entrance in the spring set off a scrum largely focused on the four incumbents and the popular South Bostonian who had run against Mayor Menino in a losing effort in 2009.

The incumbents often appeared to campaign – and were frequently endorsed – as a slate, though the occasional crack showed as they each jostled for votes. Each sought to focus on a particular issue – Murphy on finances; Connolly on education; Pressley on poverty and violence; Arroyo on youth jobs – while Flaherty criticized them, arguing they did not stand up to the mayor enough.

During the Pressley campaign’s sidewalk celebration Tuesday night, Erika Butler, a volunteer who described herself as a close friend of the councillor, carried out a large portrait of Pressley’s mother, Sandra, who died in July. “We wanted her to be here,” Butler said.

When Pressley arrived later in the evening to address the crowd and her mother’s image was held aloft and alongside her, she described the death of her mother over the summer as “the heartbreak of my life.”

“You all know I’ve been devastated, but I have been undeterred and no less determined because she didn’t die, I just absorbed her,” Pressley said. “And everything in me that is good is because of her, and I’m bolder and more fierce and more fearless than ever before.”

Rev. Gregory Groover of the Charles St. AME Church called the win a “comeback” for Pressley after her mother’s passing, describing her campaign as “extraordinary. [She] has a future in Boston. There are thousands of people, as represented by the polls tonight that believe in her, that believe in great things for her future,” he said.

Prior to entering elected office, she served as an aide to U.S. Senator John Kerry.

After settling into Peabody Square’s Carruth building and launching her political career, with a resume that included time spent as an aide to US Sen. John Kerry, Pressley won her first two-year stint on the 13-member panel in 2009, coming in fourth among the eight candidates on the at-large ballot. During her first term, Pressley has been one of only two women on the council, and its only woman of color. With former city employee Frank Baker set to replace retiring District 3 Councillor Maureen Feeney, Pressley will be the only woman on the council, come January.

As to Flaherty’s future, Jamaica Plain Patch reported that he had not ruled out a recount on Tuesday night. But he also appeared to be somewhat accepting of the results. “What can I say other than it just wasn’t in the cards,” he said, according to the website.

News editor Gintautas Dumcius contributed to this report.