Vindman is the first witness in the impeachment probe who listened in on Trump’s call with President Volodymyr Zelensky, and his testimony appears to corroborate both a whistleblower complaint lodged by an anonymous member of the intelligence community who was alarmed by accounts of the conversation, as well as a summary of the call released by the White House.

“Supposedly, according to the Corrupt Media, the Ukraine call ‘concerned’ today’s Never Trumper witness. Was he on the same call that I was? Can’t be possible! Please ask him to read the Transcript of the call. Witch Hunt!” Trump wrote, without offering any evidence that Vindman is biased against him.

“How many more Never Trumpers will be allowed to testify about a perfectly appropriate phone call when all anyone has to do is READ THE TRANSCRIPT!” the president also posted. “I knew people were listening in on the call (why would I say something inappropriate?), which was fine with me, but why so many?”

Trump last week similarly claimed to not know William Taylor, the top American envoy to Ukraine, deriding the State Department official as a “Never Trumper Diplomat” after Taylor directly tied the president to a quid pro quo with Ukraine during testimony before lawmakers.

Among the roughly four dozen tweets or retweets Trump issued Tuesday morning, the president shared missives by prominent GOP defenders in Congress including Reps. Andy Biggs of Arizona, Doug Collins of Georgia, Matt Gaetz of Florida, Mark Meadows of North Carolina, Devin Nunes of California.

Many of those messages criticized a resolution by Speaker Nancy Pelosi (D-Calif.) and House Democrats, set to be voted upon by the full chamber Thursday, formalizing the next steps of the impeachment inquiry.

“Pelosi announces they’ll finally vote to open the impeachment inquiry,” Rep. Jim Jordan (R-Ohio) wrote in a post Trump retweeted Tuesday. “Codifying a sham process halfway through doesn’t make it any less of a sham process.”

Meanwhile, allies of the White House on cable news advanced a new line of attack against Vindman — whose family fled Ukraine when he was a child — suggesting without evidence that the foreign-born public servant was more loyal to his native country than the U.S.

“We all have an affinity to our homeland where we came from. Like me, I’m sure that Vindman has the same affinity,” former Rep. Sean Duffy (R-Wisc.) told CNN on Tuesday.

“He’s entitled to his opinion,” Duffy said. “He has an affinity, I think, for the Ukraine. He speaks Ukrainian, he came from the country, and he wants to make sure they’re safe and free. I understand that.”

Duffy sought to walk back his on-air remarks in a tweet later Tuesday morning, characterizing Vindman as “an American war hero“ and writing: “My point is that Mr. Vindman is an unelected advisor, he gives ADVICE. President Trump sets the policy.“

Vindman, an Army combat veteran of the Iraq War who received a Purple Heart after being wounded in an IED attack, described himself as a “patriot” in his opening statement to lawmakers Tuesday, writing that “it is my sacred duty and honor to advance and defend our country, irrespective of party or politics.”

“Fox & Friends” co-host Brian Kilmeade acknowledged Vindman's military service Tuesday, but asserted: “He tends to feel simpatico with the Ukraine.”

John Yoo, a Justice Department official in former President George W. Bush’s administration, was more explicit in challenging Vindman’s allegiance on Monday evening.

After Fox News host Laura Ingraham promoted a story by The New York Times which mentioned that Ukrainian officials sought advice from Vindman on how to deal with Rudy Giuliani, Trump’s personal attorney, Yoo told her: “Some people might call that espionage.“

Sen. Joe Manchin (D-W.V.) denounced those comments as “despicable“ on Tuesday. “This is not normal. There's nothing normal about this,“ he told MSNBC.

Even Rep. Liz Cheney (R-Wyo.), the third-ranking House GOP lawmaker, spoke out forcefully against “questioning the dedication to country of people like Mr. Vindman” and others who have been deposed as part of the impeachment inquiry.

“It is shameful to question their patriotism, their love of this nation, and we should not be involved in that process,” she said at a news conference on Capitol Hill.

Senate Majority Whip John Thune (R-S.D.) also warned Republicans homing in on Vindman that “it would be a mistake to attack his credibility.”

“You can obviously take issue with the substance, and there are different interpretations about all that stuff,” he told POLITICO. “But I wouldn’t go after him personally. He’s a patriot.”