WORCESTER— More than half of the Police Department’s 350 patrol officers have signed cards requesting an election next month to drop the union that has represented them for the last three decades.

The upcoming decertification election will further delay the start of contract talks between the city administration and the restive officers union, which has been working without a contract since June, when the last three-year labor pact ran out.

It is unclear how a new union would approach the bargaining table with City Manager Michael V. O’Brien, who extracted key concessions in the last contract, such as deleting a “re-opener” clause that had allowed the union to renegotiate if any other municipal union got a better deal, and higher employee health insurance contributions.

Some members of the police union are said to be angry about the Fire Department contract settlement earlier this year that they think was more generous than the one to which the police agreed in 2005 and served as a model for Mr. O’Brien’s negotiations with the other city unions.

A rival union, the New England Police Benevolent Association, is seeking to replace the current union, the International Brotherhood of Police Officers, arguing that it will provide better legal representation in contract bargaining and for officers involved in grievance claims and discipline cases.

A third option could also be possible: dissolving the current International Brotherhood of Police Officers Local 378 and replacing it with an independent police association, such as the one that represents Boston police officers.

The Lowell-based New England Police Benevolent Association, which is part of the AFL-CIO labor organization and the International Union of Police Associations, broke away from the International Brotherhood of Police Officers two years ago and has persuaded about a dozen local police and corrections unions in Massachusetts and New Hampshire to join it since then.

The International Brotherhood of Police Officers is part of the National Association of Government Employees and the Service Employees International Union, which recently broke from the AFL-CIO to form the Change to Win labor federation. While the International Union of Police Associations is larger nationally, the International Brotherhood of Police Officers has historically had a stronger presence in New England.

The Police Benevolent Association filed a decertification petition with the state Labor Relations Commission in September, according to Gerald J. Flynn Jr., a Lowell police officer and former International Brotherhood of Police Officers vice president who is executive director of the PBA.

“They approached us with multiple questions about the lack of appropriate legal representation from the IBPO,” Mr. Flynn said.

The decertification campaign is partly the result of squabbling between the two unions over the services of veteran labor lawyer Richard K. Sullivan, who has been retained by the International Brotherhood of Police Officers for many years and has handled the Worcester local and other International Brotherhood of Police Officers chapters.

Mr. Sullivan has recently been in talks with the new union. Meanwhile, leaders of the Local 378 in Worcester are trying to hire him on their own as legal counsel to an independent police association or to pay him themselves as part of a local International Brotherhood of Police Officers chapter rather than through their parent organization, the state International Brotherhood of Police Officers, sources said.

Leaders of Local 378 declined to comment.

David Bernard, director of the state International Brotherhood of Police Officers, said the group is not trying to avert the election, and that it will abide by its outcome. But Mr. Bernard accused the rival union of using “misinformation” and “misleading statements” to induce more than 175 officers to request a decertification election.

“We welcome the campaign. We’re trying to run a vigorous campaign,” Mr. Bernard said. “I don’t think anyone in any way, shape or form is trying to silence the vote of the 350 men and women of the Worcester Police Department. We’re proud of our accomplishments.”

Mr. Flynn, meanwhile, denied that his union has used underhanded tactics. And he maintained that members of International Brotherhood of Police Officers locals across New England are unhappy with the dues structure of the union, saying that much of the dues money gets funneled to National Association of Government Employees and the Service Employees International Union, which represent tens of thousands of state, federal and private employees who have nothing to do with police work.

Mr. Bernard, of the International Brotherhood of Police Officers, declined to comment about the dues issue.

“Quite frankly, they’re not representing police officers,” Mr. Flynn said of the current Worcester police union.