Some departments are joining the MassCOPS organization, while others are forming their own associations. A growing number are joining the two-year-old New England Police Benevolent Association, according to state Labor Relations Commission records.

Since January of last year, nearly 90 locals across the state have joined the Lowell-based Police Benevolent Association. They include unions in Hingham, Holbrook, Mattapoisett, Middleborough, Randolph, Rockland, and Weymouth.

The International Brotherhood and its parent organizations, led by powerbrokers such as the late Kenneth Lyons, once set the labor agenda in Massachusetts. Now, police say they are leaving the IBPO to better focus on issues specific to law enforcement, rather than a broad labor agenda.

The New England Police Benevolent Association already has become a lobbying force, and its growing power could have influence as Governor Deval Patrick proposes scrapping police details and changing tuition reimbursement.

The Benevolent Association bills itself as a union led by law-enforcement officers who know the ins and outs of the profession.

"They just seem to really have the right attitude, the right perspective," said Rockland police Officer Jim Simpson, president of the Rockland police officers union.

The union, and the group that represents superior officers in Rockland, left the International Brotherhood recently to join the Police Benevolent Association.

"They understand cops better; they understand contracts and understand what we're doing," Simpson said.

"The union members . . . were just kind of dissatisfied with the representation from the IBPO. It just seemed like there was no help when you needed it."

Even locals that had no larger police representation before have joined the Police Benevolent Association, buying into the association's promise to be led by law-enforcement officers with a law-enforcement agenda.

"We just felt it was a good time to affiliate with a larger police union," said Carver police Sergeant Mark C. Duphily, whose union heard pitches by several associations before choosing the Benevolent Association.

"They are guys who know the job, who have been doing the job," he said. The union did listen to the International Brotherhood's proposals, but "something's changed" with the union. "I don't know what that is."

The Benevolent Association, which had been slowly eroding the International Brotherhood's strength over the past two years, got a big boost recently when patrol officers in Worcester agreed to join it. In doing so, they ended three decades with the International Brotherhood.

The addition of the 350-member Worcester union, which voted overwhelmingly to join the Benevolent Association, effectively drained most of the power the International Brotherhood still had in Massachusetts, observers said.

"The IBPO was a powerhouse; it is no more," said Brian Simoneau, a labor lawyer who specializes in police matters.

A spokesman for the International Brotherhood said he was too busy to respond to questions from the Globe.

The formation of the Police Benevolent Association two years ago can be traced to a political fallout between the International Brotherhood and some of its members who went on to form the new association, and some of the animosity still exists.

One factor to which the split is attributed is a lawsuit filed nine years ago by a former Lowell police officer who said she was sexually harassed by her colleagues on a bus trip to a political rally for former governor Paul Cellucci that was sponsored by the International Brotherhood. The International Brotherhood and representatives who were named, including the new director of the Police Benevolent Association, lost the case, and in 2005 the woman was awarded a $2.2 million judgment.

Several Lowell police officers were disciplined and fired. The International Brotherhood's finances sustained a major blow. On a larger scale, the suit seemed to break up the close-knit International Brotherhood association in Massachusetts.

Some of its leading representatives, including Gerald J. Flynn Jr., a Lowell police officer and one-time vice president of the International Brotherhood, split off to form the Police Benevolent Association. "The verdict was rendered quite a while ago, and you're still seeing the effects of it now," Simoneau said.

Flynn acknowledged recently that officers were disappointed with the International Brotherhood in the case, but said the break from the union had more to do with its labor agenda than the lawsuit.

The International Brotherhood of Police Officers, based in Quincy, falls under the National Association of Government Employees and the Service Employees International Union. In the meantime, the Police Benevolent Association falls under the International Union of Police Associations and the AFL-CIO.

Two years ago, the Service Employees union left the AFL-CIO toform a "Change to Win" coalition that had a mission to sign new unions from all forms of work. The International Brotherhood was lumped into that new coalition.

Flynn said the continued change in union representation, and the push for a larger labor agenda. He noted a program for a national convention several years ago that had a picture of a migrant worker being beaten by a police officer, even though the convention was supposed to be for police as well.

"Every local will tell you the same thing: The IBPO has lost its way," Flynn said. "They don't represent the interest of the police officer."