WASHINGTON — As the coronavirus surges in their states and districts, fanned by a more contagious variant exploiting paltry vaccination rates, many congressional Republicans have declined to push back against vaccine skeptics in their party who are sowing mistrust about the shots’ safety and effectiveness.

Amid a widening partisan divide over coronavirus vaccination, most Republicans have either stoked or ignored the flood of misinformation reaching their constituents and instead focused their message about the vaccine on disparaging President Biden, characterizing his drive to inoculate Americans as politically motivated and heavy-handed.

On Tuesday, Representative Steve Scalise of Louisiana, the No. 2 House Republican who said he had received his first Pfizer vaccine shot only on Sunday, blamed the hesitance on Mr. Biden and his criticism of Donald J. Trump’s vaccine drive last year. Senator Tommy Tuberville, Republican of Alabama, said skeptics would not get their shots until “this administration acknowledges the efforts of the last one.”

And Senator Roger Marshall of Kansas pointed the finger at the White House press secretary, Jen Psaki, and the director of the National Institute of Allergy and Infectious Diseases, Dr. Anthony S. Fauci.

“Every time Jen Psaki opens her mouth or Dr. Fauci opens his mouth,” he said, “10,000 more people say I’m never going to take the vaccine.”