Democrats argue that such criticism shows how single-minded the Republican Party has become about tearing down its opponents.
“Republicans have defaulted to attacking Joe Biden in a moment of national crisis,” said Senator Christopher S. Murphy, Democrat of Connecticut. “There’s this infection in the Republican Party right now, in which power matters more than anything else, more than democracy, more than the peaceful transition of power, more than winning wars overseas.”
Some Republicans have taken a different line of attack. On the far-right fringe, Representative Marjorie Taylor Greene, Republican of Georgia, declared that an independent Ukraine only exists because the Obama administration “helped to overthrow the previous regime,” a reference to the popular uprising that took down a pro-Russian president of Ukraine — actually two Ukrainian governments ago.
She, too, blamed the Biden administration, but said she opposed any intervention. Another far-right Republican, Representative Madison Cawthorn of North Carolina, was videotaped calling Mr. Zelensky “a thug,” a comment that Russian propagandists continue to use.
On the other end of the spectrum, Senator Mitt Romney, Republican of Utah, offered a more comprehensive historical analysis.
“I wish we’d have armed Ukraine more than we did, but that’s true for not just Biden, but Trump and before him,” said Mr. Romney, who warned during the 2012 presidential debate of a looming threat from Russia. “But,” he added, “Vladimir Putin is responsible for what’s happened in Ukraine,” not Mr. Biden.