Rep. Jim Sensenbrenner (R-WI) issued a scathing statement on Monday criticizing Sen. Ron Johnson, a fellow Wisconsin Republican, over his lawsuit to block health care subsidies for congressional lawmakers and staff under Obamacare.

He slammed it as a “political stunt” and “frivolous” lawsuit that would, if successful, result in a brain drain of congressional staff from Capitol Hill.

“Senator Johnson’s lawsuit is an unfortunate political stunt,” the congressman said. “I am committed to repealing Obamacare, but the employer contribution he’s attacking is nothing more than a standard benefit that most private and all federal employees receive — including the President. Success in the suit will mean that Congress will lose some of its best staff and will be staffed primarily by recent college graduates who are still on their parents’ insurance. This will make it even more difficult to fight the President and his older, more experienced staff.”

Johnson announced its lawsuit in a Wall Street Journal op-ed and a press conference Monday, flanked by former U.S. solicitor general Paul Clement and lead attorney Rick Esenberg. He is seeking to invalidate a ruling by the Office of Personnel Management, which interpreted an ambiguity in the statute to say members of Congress and staff who are required to buy insurance on the Obamacare exchanges are entitled to an employer contribution.

Johnson echoed numerous Republicans in describing the rule as as an exemption for Capitol Hill from Obamacare, calling it unjust and unfair. Some Republicans are pushing legislation to reverse the ruling.

“Senator Johnson should spend his time legislating rather than litigating as our country is facing big problems that must be addressed by Congress – not the courts,” Sensenbrenner said. “All Republicans want to repeal Obamacare, but this politically motivated lawsuit only takes public attention away from how bad all of Obamacare really is and focuses it on a trivial issue. Fortunately, Senator

Johnson’s suit is likely frivolous and will not achieve the result he’s seeking.”

Congressional staff would be put at a substantial disadvantage if Johnson’s lawsuit succeeds, as they would be the only employees in the country who are forbidden from receiving employer subsidies to buy health care.

“I’ve a great deal of respect for Congressman Sensenbrenner,” Johnson told reporters when asked about his statement. “I’m disappointed — I’m really puzzled by his reaction. … I don’t in any way shape or form believe this is frivolous or trivial, that this is a stunt. So I just respectfully disagree with the Congressman.”

Johnson was one of the wealthiest members of Congress in 2013, with a net worth of $12.5 million, according to Roll Call.