Mayor Thomas M. Menino’s dramatic exit Thursday after 20 years atop the city’s political hierarchy almost immediately stirred long-stymied ambitions, touching off what could be an unpredictable free-for-all among mayoral hopefuls.
At least a dozen would-be successors are either running for mayor or strongly considering it, colleagues and strategists said Thursday. The field will probably fluctuate and evolve rapidly as a constricted election schedule pressurizes an already highly anticipated contest.
First elected in 1993, Menino has either intimidated lurking challengers into not opposing him or beaten them handily, creating a pent-up energy that his departure will almost certainly unleash.
On Thursday, Menino’s popularity wedged potential candidates, many of whom attended his announcement at Faneuil Hall, into a politically awkward corner between the desire to establish early footholds of support and the potential penalties associated with appearing insufficiently reverent toward Menino.
“I think what’s happening is there is going to be a tremendous amount of jockeying for the next four or five, six days, and then I think it’ll settle down into a thoughtful field,” said John Fish, chairman of Suffolk Construction, who declared he had no interest in running. “And then I think it’ll become fast-paced.”
One candidate, Councilor at Large John Connolly of West Roxbury, had previously announced his intention to run, regardless of Menino’s plans. State Representative Martin Walsh, a Dorchester Democrat with close labor ties, said last week that he would seek the seat if Menino did not.
But there are more than a dozen other names traveling in political circles. Several elected officials said that Suffolk County District Attorney Daniel F. Conley of West Roxbury has made calls to sound out support. Conley reported more than $868,000 in his campaign account at the end of 2012.
Councilor Michael P. Ross of Mission Hill, Councilor at Large Felix Arroyo Jr. of Jamaica Plain, Councilor Tito Jackson of Grove Hall, Councilor Rob Consalvo of Hyde Park, Councilor Charles Yancey of Dorchester, and Council President Stephen Murphy of Hyde Park all are the subject of speculation.
As he ducked into a City Hall elevator, Yancey told a reporter, “I’m looking at it.”
Consalvo sounded a similar note late Thursday, saying, “It’s something I’m strongly looking at.” He said he hoped to announce a decision next week.
Asked if she would run for mayor, Councilor at Large Ayanna Pressley of Dorchester replied, “I’m running for reelection.”
State Representative Jeffrey Sanchez of Jamaica Plain, Massachusetts Convention Center Authority executive director James Rooney, and state Senator Sonia Chang-Diaz of Jamaica Plain were among the state officials most widely mentioned as potential candidates.
State Public Safety Secretary Andrea Cabral, the former Suffolk County sheriff frequently mentioned as a potential mayoral candidate, did not return a phone call.
There were also a few who cast doubt on speculation about their political aspirations.
Marie St. Fleur, a top City Hall aide and former state representative who was briefly a candidate for lieutenant governor in 2006, told the Globe she did not plan to run this year.
Through a spokesman, Boston Foundation president Paul Grogan said he has no plans to run for mayor.
An aide to Ralph Martin, the former Suffolk district attorney currently working as Northeastern University’s general counsel, told the Globe, “He just has no comment on anything to do with the mayor.”
At Faneuil Hall, Menino said he had no intention of influencing the outcome.
“I have no plans to pick the person to fill this seat,” he said.
But Menino’s considerable political operation spans the city and would be a valuable prize for whichever candidate can salvage portions of it.
On Thursday, political observers called the race wide open. Menino’s relatively late announcement squeezes the election’s timeline. The preliminary election is scheduled for Sept. 24, when the larger field will be whittled down to two candidates, who would then meet in a Nov. 5 final.
“I think it’s a jump ball as to who gets it, and I think the interesting thing is that anybody can get it,” said Larry DiCara, a Boston lawyer and former council president. “If, hypothetically, there are four Irish guys . . . it could be that none of them are in the final.”
Regardless of who jumps into the race, candidates will encounter a vastly changed electorate than the one that first elected Menino in 1993. That year, Menino had a leg up when Mayor Ray Flynn was appointed US ambassador to the Vatican, allowing the Hyde Park district councilor and council president to take the acting mayor’s post. That November, after an eight-candidate field narrowed to two in the preliminary, Menino beat state Representative James Brett to win the position outright.
Since then, the city’s Latino population has increased by 74 percent, and its Asian population has grown by 85 percent, according to the city’s Office of New Bostonians. At the same time, the white population has dropped from 59 percent to 47 percent.
A better comparison to the current race might be the 1983 race, when four-term mayor Kevin White opted against seeking reelection. Boston, after years of racial strife, picked Flynn, an Irish-American, and activist Mel King, an African-American, for the final.
The same year, Menino won election to his Hyde Park council seat.
Many of the prospective contenders professed a sense of disorientation as the city’s most enduring avuncular presence moved toward the door. “It has caught me as off-guard as anybody else,” Conley said.
Arroyo, who said he was considering a run, said: “He’s been the mayor since I was 14 years old. This is very real to me.”
Two lesser-known candidates have also declared for the seat: Will Dorcena, who won less than 5 percent of the vote when he ran in 2011 for an at-large seat on the City Council, and Charles Clemons, cofounder of TOUCH 106.1 FM.
As the pace of the mayoral campaign quickens, some of Boston’s most recognizable political figures are occupied elsewhere. US Representative Stephen F. Lynch of South Boston, who attended Menino’s speech, is running for US Senate in the Democratic primary against US Representative Edward J. Markey of Malden, who did not. The three Democratic candidates for an open state Senate post, state Representative Linda Dorcena Forry of Dorchester, South Boston blogger Maureen Dahill and state Representative Nick Collins of South Boston, were also in the hall.
Both the US and state Senate primaries are scheduled for April 30.
The application deadline for nomination papers for the mayor’s race is May 13.
Michael Levenson and Andrew Ryan of the Globe staff contributed. Jim O'Sullivan can be reached at James.OSullivan@