LOUISVILLE, Ky. (WDRB) -- The aggressive push to vaccinate two-thirds of U.S workers does not come as a shock to Jody Lyneé Madeira, who is a professor of law at Indiana University-Bloomington.

"[Joe] Biden said that he would try to ensure that vaccines are available for all – try to ensure they were accessible,” said Madeira. “We still have approximately 80 million Americans that are not vaccinated."

The new mandate requires employers with 100 or more workers to get vaccinated or get tested weekly.

Republican governors, in turn, have threated to sue – even Kentucky Attorney General Daniel Cameron considers the new measures unconstitutional. 

"I think it's still going to be a bit of time until we see how exactly it will work out in practice but I do think it is completely constitutional," Madiera said.

Madeira says it will likely withstand legal challenges.

"98% of companies in America don't have more than 100 employees,” said Madeira. “Legally whether it's going to be held up - Biden isn't saying 'I'm going to do this under my presidential power,' he's basically delegating this to OSHA (Occupational Safety and Health Administration) to come up with rules for these workplaces to implement this vaccine mandate."

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