An attorney for fired Minnesota Senate staffer Michael Brodkorb confirmed on Wednesday that his client and former Senate Majority Leader Amy Koch had an affair.

Brodkorb was fired late last year in the wake of revelations that Koch had a "inappropriate relationship" with a staffer, but neither he, she nor senators confirmed the two were connected. Koch resigned her leadership post but stayed in the Senate.

Brodkorb's attorney, Phil Villaume, officially disclosed the relationship in documents he gave to the state as part of Brodkorb's potential wrongful dismissal lawsuit. The documents also say that Brodkorb was treated differently than other staffers who had affairs with legislators, although they name neither the legislators nor the other staffers, Villaume said.

Reached late Wednesday, Koch said that she would not comment on anything related to the legal proceedings, and Brodkorb said all questions had to go through his attorney.

The admission came as the Minnesota Secretary of the Senate refused a mediation of Brodkorb's claims and said that Brodkorb, Koch's former executive assistant and communications director, has been engaged in "blackmail negotiations that needed to come to an end."

"Despite Mr. Brodkorb's efforts to disrupt the work of the Senate in the current legislative session, to distract members of the Senate, to extort a payment from the Senate and to try his so-called claims in the media, the Senate will not allow that to succeed," said Cal Ludeman, the Senate secretary. On Wednesday, he said the Senate will not mediate Brodkorb's claims of wrongful termination.

Brodkorb's threats to sue the Senate, and the specter that DFLers may file an ethics complaint related to the Koch issue, have been a blight on the clean slate Republicans said they wanted this year. The new admission that Koch and Brodkorb were in a relationship may mean Republicans will carry the issue with them as they attempt to hang on to their hard-won legislative majority in this fall's election.

Ludeman said Brodkorb gave the Senate no "factual basis" for his dispute, and the Senate's attorney found his claims "are without any merit whatsoever."

Villaume said Ludeman's claims are a "gross misrepresentation" of the facts and will force Brodkorb to sue in federal court, rather than settle the matter through mediation.

Villaume said Brodkorb could make claims of gender discrimination and retaliation.

"Mr. Brodkorb was treated differently from other staff," he said. He said a suit would likely be filed within 60 days.

Villaume said that he had nearly reached an agreement with the private attorney the Senate hired to deal with the Brodkorb issue to go into mediation as of yesterday. Villaume said that either Ludeman was ignorant of those talks or is being "intentionally reckless and dishonest."

"That's the end of the negotiations," he said. "We are going to go full steam ahead."

He said that he and Brodkorb plan to further discuss the situation today at a news conference.

Rachel E. Stassen-Berger Twitter: @rachelsb