All 50 Republicans in the Senate have joined together in filing a formal challenge to President Joe Biden’s recent vaccination and testing mandate for businesses with 100 or more employees, The Hill reports.

Sen. Mike Braun, R-Ind., led the GOP senators in challenging Biden’s executive rule, which was published by the Occupational Safety and Health Administration earlier this month, under the Congressional Review Act. The rule mandates that workers at businesses with 100 or more employees must either get vaccinated against COVID-19 or agree to regular testing before Jan. 4 of next year.

“While I would have much preferred that requirements not become necessary, too many people remain unvaccinated for us to get out of this pandemic for good,” Biden said in a statement earlier this month, when announcing the January deadline, according to The New York Times. The Senate GOP resolution has been referred to the Senate Health, Education, Labor and Pensions Committee and could come to a vote on the floor in December. Pennsylvania Republican Rep. Fred Keller previously introduced a similar resolution in the House.

“President Biden’s vaccine mandate is an unconstitutional invasion of what should be a personal medical decision for every American and an affront to the rights of 80 million American workers,” Braun told Fox News in a statement. “Today, my Republican colleagues and I will formally challenge this federal overreach, and I urge the Senate to vote in favor of this disapproval resolution when it comes to the floor for a filibuster-proof, simple-majority vote in early December.”