ST. PAUL, Minn. — State legal expenses associated with former Senate aide Michael Brodkorb's lawsuit now top $226,000, according to an invoice made public Wednesday.

The Minnesota Senate is paying a private firm to fight claims it mishandled Brodkorb's termination. The latest $27,700 invoice covers expenses from February through April in a case that has now stretched on for almost 18 months.

The former chief GOP communications aide was fired after reports surfaced of an extramarital affair he was having with then-Senate Majority Leader Amy Koch, who no longer holds office.

Brodkorb is suing over what he regards as a wrongful dismissal. He argues that women staff member involved in Capitol affairs were treated differently than he was.

Senate attorneys contend his firing was legitimate and have succeeded in narrowing other lawsuit claims, including allegations of defamation.

The legal invoice from the Minneapolis law firm Larkin Hoffman Daly and Lindgren details time spent analyzing the case, conferring with current and former Senate officials and Brodkorb's attorneys, and examining employment cases nationwide that deal with sex discrimination. One entry refers to the formation of a "confidentiality stipulation."

The federal case is on track for a summer 2014 trial, but a settlement conference has been scheduled for late September. At least one prior attempt to reach a settlement failed.

Brodkorb has not disclosed how much he has paid his private attorneys. The former deputy chairman of the state GOP said Wednesday he believes he is constrained by a recent pre-trial protective order from revealing that.

Dayle Nolan, an attorney for the Senate, said her read of the protective order doesn't address Brodkorb's legal expenses. They were requested as part of the initial discovery but not produced by Brodkorb's side.