As conservative media, the President and some top Republicans have signaled in recent days, Republicans on the impeachment committees plan to try to poke holes in Lt. Col. Alexander Vindman’s credibility and patriotism during his public testimony Tuesday.

According to the Washington Post, Republican lawmakers hope to paint Vindman has a low-level aide who went rogue and used an improper channel to raise alarm to White House lawyers about the call between President Trump and the Ukrainian president. The line of attack is rich, given Trump lawyer Rudy Giuliani’s backchannel mission in Ukraine that’s formed, in part, the basis of the impeachment probe.

As some top Republicans have already hinted, Republicans plan to cast Vindman as a “never Trumper” who leaked information and worked outside proper channels. On Monday, both Sen. Ron Johnson (R-WI) and House Judiciary Committee ranking member Doug Collins (R-GA) expressed in letters that they had concerns about Vindman’s judgment.

Republican leadership had a strong hand in developing the GOP’s strategy for questioning Vindman, according to the Post.

Republican investigators will reportedly frame their questioning around who Vindman discussed the now-infamous July 25 call with, an attempt to suggest that Vindman was a source for the whistleblower, whose complaint was the catalyst of the impeachment inquiry. Vindman has said in previous testimony that he doesn’t know the identity of the whistleblower.

The GOPers also plan to home in on how Vindman’s assessment and reaction to the call was different than the other two witnesses set to take the stand on Tuesday — Jennifer Williams, a top aide to the vice president and Tim Morrison, the senior director for Russian affairs at the National Security Council. Both witnesses were on the call, but didn’t raise concerns as Vindman did.

Vindman has reportedly prepped himself for the attacks and has read through Morrison’s testimony, which was in part critical of Vindman’s decision to go straight to White House lawyers to complain. The Purple Heart recipient also plans to highlight his patriotism and service to the country, a person familiar with Vindman’s thinking told the Post.