The Suffolk deputy sheriffs’ union has filed a federal lawsuit against Suffolk County seeking $4 million in deferred compensation it says the county owes its members.

The suit claims County Executive Steve Bellone’s administration is withholding the pay and accuses the county of refusing to negotiate a new contract over the past five years because the union did not support Bellone’s election campaigns in 2011 or 2015.

“We feel this is political retaliation on the part of the Bellone administration,” said John Becker, president of the Suffolk County Deputy Sheriffs Police Benevolent Association.

Justin Meyers, spokesman for Bellone, noted the administration negotiated contracts with other unions that didn’t support Bellone, including the Association of Municipal Employees and the corrections officers’ union.

“These claims are yet another attempt to bully the administration into an unfair contract for taxpayers,” Meyers said. “We remain ready and willing to sit at the table to negotiate a fair contract with the sheriffs union.”

The lawsuit, filed Wednesday in the U.S. District Court for the Eastern District of New York, names Suffolk County and names Bellone as an individual and in his official capacity. It also names the Suffolk County Sheriff’s Office and Sheriff Vincent DeMarco in his official capacity.

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DeMarco said he hadn’t seen the lawsuit yet and declined to comment.

The lawsuit accuses the Bellone administration of violating the union’s rights to free speech and association under the First and 14th Amendments. The suit seeks unspecified damages, along with $4 million in retroactive pay plus interest.

The defendants “unlawfully retaliated against Plaintiffs for the lawful exercise of their right to free speech, petition, and association as guaranteed by the United State Constitution,” the lawsuit says.

The 250-member union hasn’t had a contract for six years.

Beginning in 2008, sheriffs deputies patrolled the Long Island Expressway and Sunrise Highway under former County Executive Steve Levy as a less expansive alternative to county police officers. Top-scale deputy sheriffs make $63,000 less in base pay than police officers.

In 2011, Levy signed an agreement with deputy sheriffs guaranteeing they would continue to patrol the highways through 2017. In exchange, the sheriffs deputies agreed to defer until December 2015 $4 million of $8 million in retroactive pay they received as part of an arbitration award.

In 2012, Bellone awarded the Suffolk Police Benevolent Assocation a new contract that returned highway work to the police department.

The Bellone administration has said the $4 million was not budgeted to be paid this year because it was the subject of ongoing litigation. Sheriffs deputies sued the county in 2012 after the PBA contract returned patrol of the highways to the police department.