Michael Brodkorb says he's ready to air the Minnesota Senate's dirty secrets.

The former top Senate staffer and key GOP strategist, who was fired after having an affair with Senate Majority Leader Amy Koch, filed a wrongful termination suit Monday against his former employer that could bring allegations of discrimination, sexual affairs and backroom politics into open court.

The suit threatens to keep the affair -- and the leadership turmoil that followed -- in the public eye for months, just as Republicans are working to put their troubles behind them and make the case that voters should keep them in the legislative majority.

Brodkorb's attorneys say they will need to depose current and former legislators to prove their case that Brodkorb was treated differently from female staffers who had affairs with their legislative bosses and were not publicly fired.

The testimony could start with Koch herself, who has been quiet about the matter since she resigned from the leadership in December. She "absolutely will testify" on Brodkorb's behalf and will have "significantly more to say," said Ron Rosenbaum, her attorney.

In his suit, Brodkorb, who had been communications director for the Senate Republicans, claims that he was fired because he is a man.

His complaint alleges that "similarly situated female legislative employees, from both political parties, were not terminated from their employment positions despite intimate relationships with male legislators."

Brodkorb is a longtime Republican operative and former deputy chair and research director for the state Republican Party. He has long heard -- and sought out -- information that politicians on both sides of the aisle would rather keep secret.

On Monday, Dave Senjem, who replaced Koch as majority leader after she resigned, said the Senate is ready for the fight. He said he had no interest in settling the case and is preparing for court.

"I believe the Senate has done nothing wrong," the Rochester Republican said. "In fact, the Senate has acted carefully and appropriately in regards to this employment issue." Senate officials have said in the past that Brodkorb was an "at-will employee," meaning he could be fired at any time.

Brodkorb has sought an out-of-court settlement for months. As Brodkorb's attorney, Phil Villaume, filed the suit in Ramsey County District Court on Monday, he said his client was "disappointed that this lawsuit needed to be filed." The fact that the Senate has already spent nearly $100,000 in legal fees must, he said, "raise significant questions for the taxpayers."

The Senate has hired Dayle Nolan, at the Minneapolis firm of Larkin Hoffman, to deal with the litigation threat. According to records disclosed, the Senate has paid Larkin Hoffman at least $85,000 for work done through May.

Senjem said that "along with our attorneys, we will do everything in our power to protect the interests of the taxpayers."

Should the matter reach the trial stage, experts warn that the testimony could be broad-ranging.

Even if the Senate has a firm legal case, defending it "could be tremendously embarrassing and costly in terms of reputation," said Hamline School of Law Prof. David Larson, an expert in employment discrimination law. Larson said Brodkorb's claim that he was treated differently from female employees may rest on the details of those employees and the legislators with whom they had relations. Were those employees, like Brodkorb, in a leadership position? Were the legislators, like Koch, at the top of the command chain? If the other affairs do not share those characteristics, he may have a tougher case to make, Larson said.

Brodkorb also is suing Secretary of the Senate Cal Ludeman for publicly saying that Brodkorb was trying to "disrupt the work of the Senate," "blackmail" the Senate and "extort a payment from the Senate." He also is suing Ludeman for allegedly telling the media that Brodkorb had filed for unemployment benefits, which were denied. Brodkorb later appealed. He says the revelations violated his privacy.

Senjem said the Senate attorney will defend Ludeman from the charges. Ludeman was unavailable for comment on Monday.

The Senate has 20 days to respond to the complaint, according to the summons.

Rachel E. Stassen-Berger • Twitter: @rachelsb