A string of newly resurfaced video clips of former national security adviser John Bolton spurred President Trump and his supporters Wednesday to highlight what they described as serious credibility questions -- raised by both Democrats and Republicans -- amid the Senate impeachment trial, as the president tweeted, "GAME OVER!"

Trump linked to an interview of Bolton in August 2019 concerning Ukraine policy. In the Radio Free Europe/Radio Liberty interview clip, Bolton made no mention of any illicit quid pro quo, and acknowledged, as Republicans have claimed, that combating "corruption" in Ukraine was a "high priority" for the Trump administration.

Bolton also called Trump's communications with Ukrainian President Volodymyr Zelensky "warm and cordial," without mentioning any misconduct. It seemingly contradicted reported assertions in Bolton's forthcoming book that Trump explicitly told him he wanted to tie military aid to Ukraine to an investigation of Joe Biden. (Zelensky has said his communications with Trump involved no pressure for any investigation.)

Separately, Fox News has identified clips of Rep. Adam Schiff, D-Calif., now the lead House impeachment manager, in which he says Bolton had a distinct "lack of credibility" and was prone to "conspiracy theories." This week, Schiff said Bolton needed to testify in the trial as an important and believable witness.

"This is someone who's likely to exaggerate the dangerous impulses of the president toward belligerence, his proclivity to act without thinking, and his love of conspiracy theories," Schiff told MSNBC's Rachel Maddow on March 22, 2018, when Trump named Bolton national security adviser.

"And I'll, you know, just add one data point to what you were talking about earlier, John Bolton once suggested on Fox News that the Russian hack of the DNC [Democratic National Committee] was a false flag operation that had been conducted by the Obama administration," he said. "So, you add that kind of thinking to [former U.S. attorney] Joe diGenova and you have another big dose of unreality in the White House."

Schiff made similar arguments back in May 2005, saying in an interview with CNN's "Crossfire" that Bolton was "more focused on the next job than doing well at the last job" when he was up for nomination as ambassador to the United Nations under then-President George W. Bush.

"And particularly given the history, where we've had the politicizing of intelligence over WMD [weapons of mass destruction], why we would pick someone who the very same issue has been raised repeatedly, and that is John Bolton's politicization of the intelligence he got on Cuba and other issues, why we would want someone with that lack of credibility, I can't understand," Schiff had said.

Then-Sen. Barack Obama, in 2005, echoed those arguments, calling Bolton "damaged goods" whose appointment as ambassador means "we will have less credibility and ironically be less equipped to reform the United Nations in the way that it needs to be reformed." 

Obama separately had said that Bolton "bullies, marginalizes and undermines those who do not agree with him." Other prominent Democrats agreed at the time.

Bolton himself had admitted in the past that he would be more than willing to lie if he felt it was in the nation's interest.

“If I had to say something I knew was false to protect American national security, I would do it," Bolton said in an interview with Fox Business in 2010. Read more at FOX News