WASHINGTON -- U.S. Sen. Ron Johnson (R-Wis.) announced a lawsuit Monday to bar members of Congress and their employees from getting any employer-sponsored health insurance, saying it's not fair that the Obama administration is making him decide which of his staffers can keep federal contributions to their plans.

Before the Affordable Care Act took effect, lawmakers and staff got their health coverage from the Federal Employee Health Benefits Program. As of Jan. 1, they must get that coverage from the new health care exchanges, but the administration's Office of Personnel Management decreed in a rule finalized in September that they could still use their pre-tax employer contributions to cover most of the cost.

Johnson, a wealthy businessman who has declined to use the health care exchanges, said in his suit that the ACA does not allow the OPM to make such a change, and noted that its rule directs lawmakers and staffers to the Washington, D.C., exchange for small businesses, called DC SHOP. The federal government is not a small business, he said.

"I think it is a basic issue of fairness," Johnson said in a Capitol Hill news conference. "I really do believe that the American people expect, and they have every right to expect, that members of Congress, the political class here in Washington, should be fully subject to all of the rules, all the laws that Congress imposes on the rest of America. And that is not the case with the health care law."

The suit also argues that the provision is unconstitutional under the Equal Protection Clause, because it treats lawmakers and their staffs "differently than other similarly situated employees who obtain insurance coverage pursuant to the terms of the ACA."

Typically, lawmakers can't sue over laws and federal rules because they lack standing, but Johnson said in his case he and a staffer are personally aggrieved by the OPM rule. The suit, filed in Wisconsin federal court, notes that among the ills suffered by Johnson are that he has to decide which workers are and are not covered by the rule, and that it makes him complicit in conduct that he believes is illegal.

"I truly believe this is one of those cases ... in which I believe I do have standing, and as a result I believe I have the obligation to make this point, to overturn this rule, to try and reestablish the check and balance -- that very careful balance -- that our founders put into the Constitution to limit the size, the power and the scope of government," said Johnson, casting the issue as something bigger than health care for Hill staffers.

Johnson said it was important that those staffers and lawmakers experience what other Americans experience when they buy insurance on the exchanges without employer support, although the vast majority of Americans get insurance with tax-free help from their employers.

Johnson, who wishes to repeal Obamacare entirely, wants the court to toss the rule, and leave it up to Congress to pass a legislative fix, if there is to be one.

"This is the law of the land. If members of Congress, if this administration, don't like the law of the land, they should come to Congress to change the law of the land. They should not change it by presidential decree or presidential fiat," Johnson said.

"I think this lawsuit will hopefully provide a very long-overdue check on presidential power, expanding presidential power, particularly with this administration," Johnson said. "We are certainly seeing and I think we'll see it over the next three years, a real abuse of executive authority by this president," he added.

Still, a senior Republican from Johnson's home state of Wisconsin, Rep. Jim Sensenbrenner, slammed the suit in a press release Sunday, calling it “frivolous” and “an unfortunate political stunt.”

“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,” Sensenbrenner said. “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. “

“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 concluded.

Johnson said he isn't losing any of his staff, and that he would look at giving people raises to account for the extra cost of buying insurance.

"I'm disappointed. I'm a little puzzled by his reaction," Johnson said of his fellow Republican. "Every Republican except for two in both chambers basically voted in support of exactly what I'm trying to do in this lawsuit. I don't in any way shape or form believe that this is trivial, that this is frivolous, that this is a stunt. This is I think a very important constitutional question."

The Obama administration declined to comment on the suit, saying the litigation is still pending. But an administration official speaking on condition of anonymity echoed Sensenbrenner, saying that the OPM rule simply guarantees that Hill staffers get their insurance like the rest of the country.

“The regulation merely makes good on the law’s requirement that members of Congress and their staff purchase coverage through the same exchanges used by other Americans," the official said. "This is what Congress itself has said it intended.”

Johnson, calling the health care law a "grand scheme," countered that lawmakers tried to pass amendments that would let the government continue making contributions to staffers' insurance, and they failed.

"This was specifically debated and rejected," Johnson said.