The race for mayor of Portland came into sharper focus Tuesday, one week before the filing deadline for candidates and less than three months before city voters go to the polls.

Ethan Strimling, a former Maine legislator who finished second in the mayor’s race four years ago, formally announced Tuesday morning that he is running.

A few hours later, Mayor Michael Brennan became the first candidate to submit signatures to qualify for the Nov. 3 ballot. He had announced his candidacy for a second term in June.

And later Tuesday, City Councilor Ed Suslovic told the Portland Press Herald he will drop his effort to unseat Brennan and instead throw his support to Strimling.

While six other potential candidates have indicated they will run, the jockeying Tuesday sets the stage for a rematch of the front-runners in the 2011 mayoral election – the first citywide mayor’s race in Portland in 88 years. In that race, Brennan defeated Strimling by 1,833 votes – 26 percent to 22 percent – in a crowded field of 15 candidates.

Brennan and Strimling are both Democrats who represented the city in the Legislature.

Strimling announced his candidacy at a news conference outside LearningWorks, the nonprofit educational organization he runs in the city’s West End.

Ethan Strimling announces his bid for mayor at Learning Works in Portland Tuesday morning. Yoon Byun / Staff Photographer

“People want to be able to say I’m raising my kids in Portland because we have the best schools in the state. I work in Portland because it is where I found a great job that pays a livable wage. And I live in Portland because it’s affordable, safe and had a great quality of life,” Strimling said. “I’m running for mayor of Portland so that I can bring people together to make that vision a reality.”

Strimling spoke about his vision for the city, but did not lay out specific proposals or discuss Brennan’s performance as mayor during the past four years.

Brennan acknowledged Strimling’s candidacy Tuesday afternoon when he submitted to the city clerk more than 350 signatures he had collected to quality for the November ballot.

This will be the third time Brennan and Strimling face off in an election, Brennan said. In 2008, they both lost to Chellie Pingree in the six-way Democratic primary for the District 1 seat in the U.S. House of Representatives. Brennan came in third and Strimling finished fourth.

“I think we both know what we’re getting into,” Brennan said.

Brennan said he is “very confident” about his chances and cited as his accomplishments improvements in education, growth in the economy and a city unemployment rate that has dipped below 4 percent. He said he still has work to do to address affordable housing and bring broadband to the city.

“I think the city is moving in a positive direction,” he said. “I think the city is doing well.”

Since nomination papers became available June 30, eight people have requested paperwork so they can collect signatures to get onto the ballot. Other possible candidates include Portland firefighter Christopher Vail, who was the first choice of about 2 percent of voters in 2011; Portland activist Tom MacMillan, bar owner Ben Culver, Maine College of Art student Brendan Glass, Karl Nordli of Hillis Street and Zouhair A. Bouzrara of Grant Street.

City Councilor Suslovic once supported Brennan but had taken out papers for a possible run to unseat the mayor. He said Tuesday he will not file to be a candidate and instead will “enthusiastically” support Strimling’s campaign because he feels the city needs a change in leadership.

“We clearly need a change because things have not been going well in terms of the mayor’s relationship with the council, city staff and community groups,” he said.

Brennan has had a contentious relationship with some city councilors, as both sides continue to struggle to establish their newly defined roles outlined in the recently amended City Charter.

Councilors have asserted their right to place items on meeting agendas and have complained about a lack of communication. Some have openly questioned whether having an elected mayor creates confusion and additional work for city staff, especially the corporation counsel, city clerk and city manager, all of whom work closely with the mayor but report to the council as a whole.

Portland Mayor Michael Brennan, right, drops off signatures to qualify for the ballot for re-election at the City Clerk’s office Tuesday.

City Councilor Nicholas Mavodones was also considering a run to unseat Brennan. But Mavodones has instead taken out nomination papers to seek re-election to his at-large council seat in November. He has scheduled a news conference for Wednesday and is expected to formally back Strimling, one more sign of the friction between the council and Brennan.

Strimling’s entry into the race had been widely expected, but comes at about the last possible moment to launch a campaign. The deadline to turn in at least 300 signatures is August 25 and he pulled nomination petitions at City Hall on Tuesday.

Strimling, 47, has been the co-author of a politics column in the Maine Sunday Telegram and a senior political analyst for WCSH. He said he is now done with both of those activities.

Strimling’s first run for political office was in 1999, when he lost a Portland City Council race by 24 votes. During a recount, a divided council awarded Strimling 35 disputed ballots, but he announced he would step aside after opponent Jack Dawson appealed the decision in Maine Superior Court.

Strimling, who lives in the West End, served in the state Senate from 2002 to 2008. The Democrat was chair of the Labor Committee, Criminal Justice Committee and the Homeland Security Task Force during his time in the Legislature. Prior to that, he ran a national political action committee focused on electing young leaders and provided policy analysis for U.S. Rep. Tom Andrews, D-Maine.

The son of a New York City actor, Strimling attended The Juilliard School in Manhattan before moving to Maine when he was 20. He attended the University of Maine, then earned a master’s degree in education from Harvard University.

Although sharing oversight of city government with the council, Portland’s mayor serves full time and receives a $70,000 annual salary.

Unlike most elections in the United States, the winner of Portland’s mayoral race is determined through a ranked-choice process. Voters rank the candidates in order of preference, and if no candidate wins a clear majority, the candidate with the fewest first-place votes is eliminated, and the candidate’s second-choice votes are distributed to the remaining candidates. This continues until one candidate emerges with a clear majority.

The city clerk’s office announced Tuesday that it will host an open house at 5:30 p.m. Aug. 20 for a presentation on ranked choice voting. The demonstration will be held in the State of Maine Room on the second floor of Portland City Hall.