Sen. Ron Johnson, R-Wis., plans to file a lawsuit against the Obamacare regulation that allows congressional staff to keep their employer contributions for use towards the purchase of a health insurance plan.

Johnson explained that he went through the process of submitting a comment with the Office of Personnel Management challenging the regulation "so that I can hopefully establish standing to challenge this in court if it goes that far," as he explained to reporters. Johnson said that seven of his aides joined him in submitting the comment.

Obamacare as written deprived congressional staff of their employer contribution; the OPM regulation attempts to reverse that. Sen. David Vitter, R-La., has pushed an amendment to the continuing resolution that funds government that would reverse that regulation.

"I think they're on completely indefensible ground," Vitter said during the joint press conference with Johnson when asked if his legislation was important enough to be a sticking point that leads to a government shut down.

"If [the shut down happens] because Democrats won't accept treating Washington like it treats America, I think that's an important message for all Americans to hear," he said.