Mayor Thomas M. Menino declared last year that US Senator Scott Brown, a Republican, was unbeatable, making a bold statement for a Democrat whose political muscle can be crucial for turning out votes for his party.
Menino will apparently test his own prognostication: He is expected to endorse Brown’s challenger Friday, throwing his support and his army of political operatives behind Democrat Elizabeth Warren, according to several people with knowledge of the plan.
Menino is scheduled to appear with Warren at 4 p.m. at a rally in Roslindale Square, according to the individuals, who insisted on anonymity because they had not been authorized to speak. Warren’s campaign also declined to discuss the endorsement, which will end months of speculation about Menino’s role in a race that could tip the balance of the US Senate.
“It’s a very big deal,” said Peter Ubertaccio, a political scientist at Stonehill College. “He can assist statewide Democratic candidates like very few other officeholders.”
A Menino endorsement brings more than the mayor’s charisma to the ticket; he can deliver a political machine capable of turning out votes.
News of the endorsement was first reported Thursday on the website of the Dorchester Reporter. Brown’s campaign declined to comment, but one Republican political analyst suggested that Warren’s campaign shrewdly timed the endorsement for the day after the candidates’ first debate.
“This is a backstop for the debate,” said the analyst, Todd Domke. “If she doesn’t do well, the campaign can use this endorsement to change the subject. It guarantees a debate victory. They have a big media event the next day to claim victory and claim momentum, and if necessary, to change the subject.”
Regardless of the outcome of the debate, Domke and other political analysts agreed that Menino’s support could be pivotal in a close election. The real question is how hard Menino pushes his get-out-the-vote machine in November. In 2010, Menino’s foot soldiers helped Governor Deval Patrick win reelection.
“They have a real army of people they can put on the street,” said Michael J. McCormack, a former Boston city councilor. “That means phone calling, identifying the good voters, door knocking. What they did for Patrick was very, very impressive. If they do the same thing for Warren, it could be a game-breaker.”
Menino may be a Democrat, but he has a history of playing hard to get with other Democrats running for statewide office. His political lieutenants have worked hard in many high-profile Democratic campaigns, but the machine has also remained idle when Menino liked the Republican across the ticket.
The most infamous example emerged in 1998, when Menino grudgingly endorsed Democrat Scott Harshbarger for governor a few weeks before Election Day. Menino and Harshbarger clashed before the campaign, and the mayor had a close relationship with the acting governor at the time, Paul Cellucci, a Republican. Menino’s endorsement of Harshbarger proved largely hollow. Cellucci won.
Warren and Menino did not have a significant political history before she embarked on her candidacy. In fact, she had not yet entered the race when Menino said that no one could beat Brown. But since Warren became the clear Democratic nominee, Menino has been coy about his support.
Until word leaked of Friday’s planned endorsement of Warren, some pundits had seen Menino’s silence in the past months as support for Brown.
“He was playing a signaling game, making sure that if Senator Brown is reelected that he remains on good terms with him,” said Jeffrey M. Berry, a political science professor at Tufts University. “He was communicating very loudly: ‘Look I’m in a difficult situation. I’m eventually going to have to endorse Elizabeth Warren. But I want you to know I like you, too.’ ”
Menino and Brown have developed a close relationship, often appearing together at events in Boston. Menino has described Brown as a gifted retail politician, a high compliment from a man who sees his best asset as relating to everyday people.
Despite their similarities, Menino and Brown are often on opposite sides of political debates. Brown’s votes in the Senate have at times been at odds with issues important to the mayor, such as supporting budgets that cut money for public housing, community health centers, and grants.
Over the past few months, Menino has gotten to know Warren, meeting her at public events and speaking with her by phone. The mayor has watched her campaign, listened to her stances on issues, and gradually been drawn into her camp, according to people close to Menino.
Earlier this month, Vice President Joe Biden asked Menino to address the Democratic National Convention, where Warren had a high-
profile speaking slot. Menino made clear he was on board with the Democrats’ message, saying he would endorse the Senate candidate who would move the country forward, a major theme of the convention.
For Democrats, a Warren loss could cost control of the US Senate. A Brown victory could hand control of the body to Republican minority leader Mitch McConnell.
“The Senate is at stake,” said Lawrence S. DiCara, a Democrat and former city councilor. “The issue is not Scott Brown. The issue is Mitch McConnell.”
Andrew Ryan can be reached at email@example.com.