Suffolk County is facing a federal lawsuit from its deputy sheriffs union.

According to the Suffolk County Deputy Sheriffs PBA, the county owes $4 million in wage concessions, and it is now suing to get that money.

The union filed a federal lawsuit on Wednesday, claiming that Suffolk Executive Steve Bellone is denying union members deferred wages in retaliation for not supporting his campaign in 2011.

The lawsuit is the latest twist in a long battle that began in 2011, when then-Executive Steve Levy made an agreement with the union to keep deputy sheriffs patrolling the Long Island Expressway and Sunrise Highway through 2017. In return, the union agreed to defer $4 million to $8 million in retroactive pay increases until 2015.

But Bellone, who won his election in 2011 with the endorsement of the police union, signed a new contract with that police union in September 2012 that returned highway patrol work to them.

A state Supreme Court justice upheld the deputies' agreement with Levy, but the county appealed, claiming that the Legislature never ratified the pact. Late last year, Bellone's administration told the deputy sheriffs union that it has no intention of paying back the $4 million in wage concessions.

Union President John Becker says that in addition to withholding payment, the county has delayed negotiating a new contract with the union.

In response, a spokesman for Bellone says multiple negotiations were held with multiple unions who didn't support Bellone in 2011, and that they are willing to negotiate a fair deal with the sheriffs union.

A decision in the lawsuit is not expected until 2017.