Mayor Tom Menino: Will not seek re-election this year. Photo by Bill Forry Mayor Thomas Menino will announce tomorrow he is not running for a sixth term, sources told the Reporter on Wednesday night.

The move ends a 20-year hold on the only job he has said he’s ever wanted, sets up an epic rumble for the first open mayoral seat in 30 years, and comes after a prolonged bout of speculation about whether he’d make another bid.

Menino’s expected announcement was first reported by David Bernstein, the former political reporter for the Boston Phoenix, an alternative weekly that folded earlier this month. Menino will make the announcement at 4 p.m. in Faneuil Hall.

Multiple calls to Dot Joyce, Menino’s press secretary, were not returned on Wednesday night.

The list of candidates who are running for mayor – at this point City Councillor At-Large John Connolly and a pair of longshots – is expected to grow in the coming days. State Rep. Marty Walsh (D-Dorchester), Suffolk District Attorney Daniel Conley, and City Councillors Tito Jackson, Rob Consalvo and Felix Arroyo are all expected to take a look, if not plunge immediately into the race.

Menino was elected to the City Council in 1983 and grabbed the job of City Council president ten years later. He was named acting mayor when Ray Flynn was tapped as ambassador to the Vatican. In the election that followed, voters chose Menino over Dorchester state Rep. Jim Brett, and repeatedly returned the mayor to City Hall’s top job.

Menino, a Hyde Park Democrat who had worked as a political operative for state Sen. Joe Timilty, became the city’s first Italian-American mayor. He easily beat back occasional challengers like Peggy Davis-Mullen, Maura Hennigan and Michael Flaherty.

His legacy will be multi-faceted: The creation of the so-called “Innovation District” in South Boston, drawing start-ups to the waterfront; the city’s Main Streets program, which works with businesses to improve storefronts and neighborhoods through technical assistance and early support for gay marriage.

“Amid all the rhetoric, much of what we see is politicians working to get a leg up,” he said in a March 2011 speech to the Boston Municipal Research Bureau. “I am about the politics of getting going. In Boston, when we hit a roadblock, we return to the drawing board, we innovate, and we move ahead.”

Reforming and improving the city’s education system has proved to be a difficult task, though the mayor has made strides and an advisory committee of parents and academics this year delivered an overhaul of an unpopular school assignment system that his administration acknowledged was long overdue.

What the future holds for Menino is not immediately clear. He recently told a reporter he envisioned working with kids after he retired from public office.

Earlier this week, Menino stood in front of 500 business leaders and potential rivals at the Boston Municipal Research Bureau's annual luncheon and laid out city’s progress. “I have always said that the status quo is moving backward,” he said. “Just moving forward isn’t enough. We have to move ahead aggressively and relentlessly. This is the mindset of other leading cities across the world. This is what today’s competitive landscape demands, and we demand it of ourselves. Every day. In every corner of our city. In every sector of our economy. In every school in our city. In every budget we build. In everything we do. We pile progress on top of progress. And that job is never done. Thank you and now let’s get back to work.”