Hoosier Sen. Mike Braun is leading the Republican effort to challenge President Joe Biden’s upcoming COVID-19 vaccine mandate on private employees.

Braun, the ranking member of a Senate committee on employment and workforce safety, and 40 other Senate Republicans announced Wednesday they are moving to disapprove and nullify Biden’s vaccine mandate under the Congressional Review Act.

Fellow Hoosier Republican Sen. Todd Young , who is up for reelection in 2022, also joined the effort.

“Since the announcement of President Biden’s vaccine and testing mandate in September, I have led the charge to strike down this vast overstep of authority by the federal government,” Braun said in a statement. “Today, we are one step closer to protecting the liberties of millions of Americans in the private sector workforce under the Congressional Review Act.”

The Biden administration announced the upcoming mandate in September and is expected to issue a rule this week mandating vaccination requirements for businesses with more than 100 employees. Those who don’t get vaccinated would have to be tested weekly.

“Many of us are frustrated with the nearly 80 million Americans who are still not vaccinated,” Biden said when he first announced he would pursue the mandate. “This is not about freedom from personal choice, it’s about protecting yourself and those around you.”

Indiana Republicans, including Gov. Eric Holcomb and others who have encouraged Hoosiers to get the vaccine, have slammed Biden for the decision.

The resolution rolling back the rule would need to be passed by both the House and Senate and signed into law by Biden. If he vetoes it, the resolution would need a two-thirds vote in each chamber. Republicans do not have a majority in either chamber.

Braun has not responded to numerous questions from the media on his vaccination status. Young has been fully vaccinated.

In Indiana, just under 3.38 million Hoosiers are fully vaccinated.