WASHINGTON (NEXSTAR) — The White House rolled out new nationwide vaccine mandates Thursday in an effort to end the pandemic.

The new rules will impact roughly 100 million private sector workers across the country. According to the newly released rules, private sector companies with more than 100 employees will be required to ensure their employees are fully vaccinated by Jan. 4 or be tested weekly for COVID-19.

Health care workers won’t have the testing option and must get vaccinated.

Republicans are railing against the new rules, calling them unconstitutional.

Members of the White House Coronavirus Task Force are defending the effort and insisting the new measures will save lives.

Centers for Disease Control and Prevention Director Rochelle Walensky said the new mandates are necessary to save lives and prevent variants from spreading.

“We’re continuing to have about 75,000 cases every single day,” Walensky said. “We know the most destructive thing in the workforce is to have a COVID outbreak.”

Many Republicans say the rules could backfire.

“I think you’ve got an extremely tough sale,” said Sen. Richard Burr, R-N.C.

Sen. Tommy Tuberville, R-Ala., says he’s concerned the mandates could worsen labor shortages and supply chain problems.

“In Alabama we’re having problems with it,” Tuberville said. “We have 5,000 defense contractors … you just can’t replace a rocket scientist if one doesn’t take the vaccine.”

Sen. Mike Braun, R-Ind., called the mandates federal overreach, saying it’s “the most frightening ultimatum business have had to contend with.”

Two dozen states are threatening legal action. The White House says it’s not concerned. 

“We’re pretty confident … the administration clearly has the authority to protect workers,” White House Deputy Press Secretary Karine Jean-Pierre said.

The White House also said they do not believe mandates will impact supply chain issues.