MADISON (AP) - A federal judge will hear arguments this week on whether to toss a U.S. senator's lawsuit challenging rules that force congressional members and their staffs to obtain government-subsidized health insurance through small business exchanges.

Republican Sen. Ron Johnson of Wisconsin contends that senators, representatives and their employees aren't eligible for the exchanges under the federal health care law because they work for a government that employs millions. He also argues that premium subsidies that congressional members and staffers receive will foster resentment among his constituents.

Republicans have spent years railing against President Barack Obama's health care reform law, known as the Affordable Care Act. Johnson isn't attacking the act itself, focusing instead on rules imposing the act on Congress. But he's using the lawsuit as a mechanism to complain more broadly about what he sees as Obama unilaterally rewriting the act.

"This lawsuit offers a landmark opportunity to re-establish the balance between the executive and legislative branches of government," Johnson said in a statement last month.

Government attorneys have asked U.S. District Judge William Griesbach to throw the case out of court. They argue Johnson hasn't shown how the rules hurt him or his staff.

"This allegation ... describes an abstract injury that might or might not occur depending on how third parties (Senator Johnson's constituents) perceive and react to (the) regulations," U.S. Justice Department attorneys wrote.

Griesbach, who was appointed by former President George W. Bush, has scheduled a hearing for Monday in Green Bay to consider dismissing the lawsuit.

The dispute stems from language Sen. Chuck Grassley, R-Iowa, inserted into the act during debate. Under those provisions, the only health care plans the federal government can offer to congressional members and staffers must come through an exchange. That means members and staffers must leave their old government health plan, which subsidized 75 percent of their premiums through tax-free contributions.

Grassley's move was a political ploy designed to force the act's Democratic supporters into the same situation as uninsured Americans. But the problem is that congressional members and staffers make too much money to qualify for government subsidies other exchange users can receive, stoking fears that staffers would flee for the private sector because they wouldn't be able to afford full premiums.

Enter the U.S. Office of Personnel Management. An arm of Obama's administration, it published rules in October 2013 stating the only health insurance plans available to congressional members and staffers must be offered through the small business exchanges but allowing them to continue receiving the premium subsidies they got under their old plan.

Johnson filed the lawsuit in January, demanding a judge invalidate the rules. Federal employees can't legally use small business exchanges because they're limited to people who work for businesses with fewer than 100 employees, he contends. What's more, he says, the rules hurt his credibility with constituents because the government's premium contributions put him "in a privileged position."

Dozens of Republican House and Senate members have rallied behind Johnson, arguing in court filings the rules are another example of Obama trying to change the law on his own. They point to a number of administration moves in addition to the congressional rules, including postponing requirements that employers supply workers with health insurance and extending subsidies to people who obtain insurance through federally established exchanges even though the act says only those who go through state-built exchanges are eligible for help.

"The remedy to address ... unpopular laws is through their repeal or modification by Congress, not through the President turning those laws on-and-off," they wrote.

Government attorneys say those points don't matter because Johnson lacks standing to sue.

"These principles do not fall away merely because a Member of Congress is accusing the Executive Branch of acting unlawfully," they wrote.

If Johnson prevails the rules would be invalidated. The provisions in the act would then apply to the senators, representatives and staffers' health care coverage. They could enter exchanges for individuals sans subsidies or they could seek insurance elsewhere on their own.

If congressional members don't like that prospect, Johnson's attorney, Rick Esenberg said, they can amend the act or raise staffers' pay.