“We’re talking Ukraine,” thundered Representative Jim Jordan, Republican of Ohio, in 2019, describing the country as “one of the three most corrupt countries on the planet.” The setting was a hearing for Mr. Trump’s first impeachment, over his efforts to pressure Ukraine’s president, Volodymyr Zelensky, into digging up political dirt on Mr. Biden.

Now such voices are fading, as the bulk of the Republican Party tries to get on the right side of history amid a brutal Russian invasion of Ukraine. Republicans are among the most vociferous champions for the United States to amp up its military response, and are competing to issue the strongest expressions of solidarity with Ukraine’s leaders.

Senator Roger Wicker of Mississippi has taken up Mr. Zelensky’s call for a western-enforced no-fly zone. Senator Rick Scott of Florida said deploying U.S. ground troops to Ukraine should not be “off the table.” Senator Lindsey Graham of South Carolina encouraged the assassination of President Vladimir V. Putin of Russia to save a nation that many in his party had previously portrayed as hardly worth saving.

“What was sort of a problematic, corrupt place is now the defender of freedom,” Mr. Graham quipped about his colleagues’ changing tunes.