On Tuesday, an under secretary of state, David Hale, told the Senate Foreign Relations Committee that none of the allegations of Ukrainian interference were true.

But if anything, support among Republican legislators for the conspiracy theory continues to grow.

Time and again during the impeachment hearings, House Republicans sought to distract from, or even justify, Mr. Trump’s attempt to strong-arm Ukraine by floating the specter of Ukrainian saboteurs. Representative Devin Nunes, the top Republican on the Intelligence Committee, called for the panel to refocus its investigation on the former Soviet republic.

The day after Dr. Hill’s testimony, Mr. Trump regaled “Fox & Friends” with wild assertions that the F.B.I. never properly examined the hacked server because it had been handed over to a shadowy Ukrainian company called CrowdStrike.

Among the flaws in his claim: CrowdStrike, the cybersecurity firm that the Democratic National Committee hired to respond to the hacking, is based in California and owned by Americans. One server hacked by the Russians is actually still in the D.N.C. offices in Washington.

This whole fantasm haunts Washington in tandem with Attorney General William Barr’s aggressive efforts to discredit the F.B.I. investigation of Russian ties to the 2016 Trump campaign. The Justice Department’s inspector general has reportedly concluded that the basis of that investigation was legitimate and that claims of deep-state manipulation were nonsense, leaving Mr. Barr fuming.

To be clear, plenty of Ukrainians openly opposed Mr. Trump’s candidacy for fear he was too supportive of Mr. Putin. Mr. Trump’s public acceptance of Russia’s illegal annexation of Crimea prompted particular concern. So did ties between Paul Manafort, Mr. Trump’s former campaign chairman, and pro-Russian politicians in Ukraine. Serhiy Leshchenko, an anti-corruption crusader and former member of Ukraine’s Parliament , worked to publicize secret payments Mr. Manafort received for his work in Ukraine, which eventually led to Mr. Manafort’s resignation from the campaign.

American intelligence agencies have determined that such efforts were scattershot and in no way comparable to the top-down, systematic, aggressive campaign by Moscow — directly overseen by Mr. Putin — to disrupt the race.