Even in states where other vaccines are required, the G.O.P. is enraged by Biden’s mandate.

Mr. Biden is on strong legal ground, according to experts in public health law, because his actions are based on federal worker safety laws. They claim that Republican governors who argue that vaccine requirements violate personal liberty should review their own state policies.

Mr. Reeves’ words, according to Lawrence O. Gostin, a public health law expert at Georgetown University, are “pure hypocrisy.” “How can he claim that an order issued by the president to keep workers safe, with congressional support, is an overreach or in any way unconstitutional?”

Mr. Reeves’ spokeswoman, Bailey Martin, refuted Mr. Gostin’s claim. “The only individuals who are being hypocritical are President Biden and his administration, who have insisted for months that the vaccine will not be mandated,” says the author.
Before the epidemic, Republican distrust of vaccines was growing; when Donald J. Trump ran for president in 2016, he defied mainstream science by resurrecting the disproved notion that vaccines cause autism. Some governors now contend that, given the country’s deep divisions, widespread fear of federal action from Washington would be unproductive. They claim that vaccines are safe and effective and that people should be able to make their own decisions.

Dr. Jha said Mr. Biden had in fact done Republicans a favor.

He explained, “What the president does is he offers political cover for Republican leaders, who will shout loudly because it’s politically convenient.” “However, I believe that many of them are relieved since they no longer have to go through the difficult process of persuading their constituents.”

When the highly virulent Delta variety began ravaging their towns and flooding hospitals, several elected Republicans, including Senate Minority Leader Mitch McConnell of Kentucky, began begging with people to get vaccinated. The majority of Republican governors who have criticised Mr. Biden have said something similar.