New England's most powerful Teamsters leader is facing a likely suspension from his post after an independent oversight board accused him of threatening to retaliate against union members running against his preferred candidates in a hotly contested union election in Rhode Island.

Sean O'Brien, head of Teamsters Local 25 in Charlestown and president of a council that handles Teamsters disputes throughout New England, reportedly told union members during an election rally that opponents of Joe Bairos, secretary-treasurer of Providence's Local 251 and an O'Brien ally, were harming the union's strength and stability.

"I've got news for you, anyone who takes on my friend, Joe Bairos and his team, or Local 251, they've got major problems," O'Brien said, according to transcripts of the union hall rally in Rhode Island during late summer. "They'll never be our friends. They need to be punished. They need to be punished and they need to be held accountable for their actions, trying to divide and tear down this local."

Those words were enough for the Independent Review Board, created by court decree in the 1980s to oversee the corruption-plagued Teamsters, to recommend charges against O'Brien for violating union rules about intimidating members during an election.

O'Brien, who has led the local since 2006, has told members that he expects to be suspended from for an unspecified period of time, according to union members who attended a Sunday meeting in Charlestown, where O'Brien briefed Teamsters about the controversy engulfing him.

O'Brien could not be reached for comment.

During recent testimony before Independent Review Board investigators, O'Brien said that he used a "poor choice of words" at the recent Rhode Island rally and that he only meant to convey opponents would be "punished at the ballot box," according to the board's report.

Bret Caldwell, a spokesman for Teamsters International president James P. Hoffa, would only say the national union has received the Independent Review Board’s report about O'Brien.

The controversy comes at particularly sensitive time for O'Brien, a Hoffa ally who serves on the Teamsters' national governing board. If his suspension runs through next June, O'Brien may be disqualified from running for national office again in 2016, said David Levin, an organizer at Teamsters for a Democratic Union, a group that opposes Hoffa.

The incident is the latest black eye for Boston area Teamsters. Last year, O'Brien's Local 25, which has about 11,000 members, had to take over the former Teamsters Local 82 

In Rhode Island, O'Brien has allied himself with a slate of Hoffa supporters against candidates backed by Teamsters for a Democratic Union. Elections at the 5,000 member Rhode Island local are being held throughout this month, amid allegations of voter intimidation and failure to deliver ballots to supporters of TDU candidates.

Despite this controversy, O'Brien has won guarded praise from some industry executives, including Hollywood movie makers who work with the Teamsters on movies filmed in Boston, for his leadership of Local 25, which had been wracked by scandals. One of his predecessors as leader of Local 25, George Cashman, pleaded guilty to embezzlement charges in 2003 and later served time in prison. O'Brien has led the local since 2006.

Even some of O'Brien's critics say he's generally fair in running Local 25 and the Teamsters Joint Council 10, the New England umbrella group that settles various disputes between Teamsters' locals. "He's been a proponent of more democracy in the union, but I'm very disappointed with his 'punish' remarks," said Nick Williams, the campaign manager for TDU-backed candidates in Rhode Island.

O'Brien almost became a reality-show television star in 2012, when the A&E Network announced it was partnering on a pilot program called "The Teamsters," with Boston-native and actor Mark Wahlberg, whose father was a local Teamsters truck driver. A&E, however, dropped the pilot, before the current Local 25 controversy.