Sen. Ron Johnson’s lawsuit to stop the federal government from contributing to staff health care costs might make him public enemy No. 1 in the Senate’s hallways.

The Wisconsin Republican filed the suit Monday in federal district court in Green Bay, Wis., against the Office of Personnel Management, seeking to overturn the administrative decision that allows members and staff who transitioned onto the D.C. health care exchange from the federal benefits plan to continue receiving employer contributions.

Johnson is dismissing criticism of the legal action, including from a senior Republican from his home state, Rep. Jim Sensenbrenner. Johnson called the contention that senior staffers could desert the Capitol complex over increased out-of-pocket health care costs “one of the canards” that opponents use in the debate.

Longtime observers have expressed concern about lasting damage to the institution, however. Johnson’s move has echos of the ongoing effort by Sen. David Vitter, R-La., to secure a vote on an unpopular amendment that would address the same subject matter.

Sensenbrenner issued a sharply worded statement on Sunday, ripping the suit a day before it was filed.

“Senator Johnson’s lawsuit is an unfortunate political stunt,” Sensenbrenner 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 said at a news conference Monday that he had built extra funds into his Senate office budget to allow salaries for some staffers to be increased to compensate for the lost contributions for their health care. Johnson also said that, unlike in the private sector, individual Senate offices aren’t responsible for insurance.

“On a case by case basis, that’s exactly what I’m considering, you know, per staff member,” Johnson said. “I’m just naturally frugal and so … for the three years I’ve been here in Congress, every year I’ve underspent my budget by at least a half a million dollars.”

Senate Majority Leader Harry Reid quoted Sensenbrenner on the Senate floor Monday afternoon to criticize Johnson’s legal maneuvering.

“It would take away the insurance of the people here that are working in this body right here, all these people right here, all of them, it would take away … their insurance, plus all our staffs that are here, take it away,” Reid said.

Under the legal theory advanced by Johnson, counsel Rick Esenberg and former Solicitor General Paul Clement, the staffers and lawmakers deemed eligible for federal contributions through the D.C. small business exchange would lose that benefit, which exists due to the unusual case of federal workers being put into the exchange system that really was not designed for their needs.

Esenberg, the founder and president of the Wisconsin Institute for Law & Liberty, is counsel on the suit. Johnson has retained Clement, who argued against the constitutionality of the health care law at the Supreme Court, for possible appeals.

“I knew this was coming,” Johnson said of the health care changes. He also said Monday he is not against individuals taking advantage of the system implemented by the OPM, even though he wants to bring it to a halt.

“I imagine all … my staff members, I think most people here in Congress and staff did take the employer contribution, I’m not being critical of that,” Johnson said. “I’m being critical of the president who knows no legal bounds and is … doing things by presidential decree.”

Johnson held a news conference Monday with Esenberg and Clement to announce the court filing in the ornate room named for former Majority Leader Mike Mansfield, just off the Senate floor, even though he conceded he is seeking campaign contributions to pay the legal costs.

“The Senate Ethics Committee did allow me, as a way to raise funds to do this, is to do it through my campaign committee, and so that’s another way I can fund this. So, I can do a combination or you know, all of one or all of the other,” Johnson said. “I’m hoping to be able to you know, quite honestly, raise funds through my campaign committee.”

Johnson should have no difficulty paying for the court costs out of pocket. He landed at 29 on the most recent edition of Roll Call’s 50 Richest list, with an estimated minimum net worth of $12.47 million.

“I think this is such an important issue that … I’m more than willing to fund personally or utilize those, those limited campaign funds,” Johnson said.