Washington CNN  — 

House Republican Conference Chair Liz Cheney of Wyoming said on Tuesday that it is “shameful” to question the patriotism of Lt. Col. Alexander Vindman, the White House National Security Council’s top Ukraine expert, who is testifying in the House impeachment inquiry.

“I also want to say a word about something else that’s been going on over the course of the last several hours and last night, which I think is also shameful, and that is questioning the patriotism, questioning the dedication to country of people like Mr. Vindman, Lieutenant Colonel Vindman, who will be coming today, and others who have testified,” Cheney said at a House GOP leadership weekly news conference.

“We need to show that we are better than that as a nation,” Cheney said, adding, “Their patriotism, their love of country, we’re talking about decorated veterans who have served this nation, who have put their lives on the line. It is shameful to question their patriotism, their love of this nation, and we should not be involved in that process.”

Cheney did not specify to whom she was referring in her comment during the news conference, but it comes as Vindman, a decorated veteran who was born in Ukraine, has faced attacks from President Donald Trump and other Republicans.

Former Republican Rep. Sean Duffy of Wisconsin, who is a CNN contributor, argued during an appearance Tuesday on CNN that Vindman has an “affinity” for Ukraine and suggested that Vindman is more concerned about its defense than US policy.

“It seems very clear that he is incredibly concerned about Ukrainian defense. I don’t know that he’s concerned about American policy, but his main mission was to make sure that the Ukraine got those weapons. I understand that; we all have an affinity to our homeland where we came from,” Duffy said, adding, “He has an affinity, I think, for the Ukraine.”

Later on Tuesday, Duffy tweeted, “Lt. Col. Vindman is an American war hero. As I said clearly this morning on air ‘I salute Mr. Vindman’s service.’ My point is that Mr. Vindman is an unelected advisor, he gives ADVICE. President Trump sets the policy.”

Vindman is expected to tell House impeachment investigators on Tuesday that he was so troubled by the President’s July phone call with Ukraine’s President that he reported his concerns to a superior, according to a copy of his opening statement obtained by CNN.

According to his prepared remarks, Vindman also plans to tell House lawmakers that he has “dedicated my entire professional life to the United States of America,” saying, “For more than two decades, it has been my honor to serve as an officer in the United States Army. As an infantry officer, I served multiple overseas tours, including South Korea and Germany, and a deployment to Iraq for combat operations. In Iraq, I was wounded in an IED attack and awarded a Purple Heart.”

In the remarks, Vindman also describes how his family fled the Soviet Union when he was a child.

“The privilege of serving my country is not only rooted in my military service, but also in my personal history,” the planned remarks state. “I sit here, as a Lieutenant Colonel in the United States Army, an immigrant,” he will say. “My family fled the Soviet Union when I was three and a half years old. … I am a patriot, and it is my sacred duty and honor to advance and defend our country, irrespective of party or politics.”

Trump targeted Vindman as a “Never Trumper” in a tweet on Tuesday morning, despite the fact that there is no indication he is.

“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!” the President tweeted.

Cheney isn’t the only congressional Republican defending Vindman.

Sen. John Thune of South Dakota, the No. 2 Senate Republican, said on Tuesday, “I don’t at all question his patriotism. I respect his service. He’s a Purple Heart, and I think it would be mistake to attack his patriotism.”

Republican Sen. Mitt Romney of Utah similarly said, “I think that is misplaced, very unfortunate. This man is a decorated American serviceman, and I have full confidence in him as an individual and his patriotism.”

CNN’s Ted Barrett, Betsy Klein, Devan Cole and Paul LeBlanc contributed to this report.