The revelation brings President Trump one step closer to becoming the third president in U.S. history to be acquitted of articles of impeachment. But that vote may not come until next week.
"Those offering to tell the truth should be welcomed, not pilloried," Andrew Napolitano wrote.
"I don't like the idea of people making John Bolton out to be a liar," Fox & Friends co-host Brian Kilmeade said.
Fox Business host Lou Dobbs called former National Security Adviser John Bolton "more of a turncoat than anyone realized" on his television program Wednesday. Dobbs also said that GOP senators who vote for witnesses during the ongoing impeachment trial are trying to "sabotage the Republican party."
The National Security Council claims Bolton's manuscript contains both classified and Top Secret information. Bolton's lawyer doesn't think so.
Conservative preacher Rodney Howard-Browne insisted Jesus would have physically attacked former National Security Adviser John Bolton for his supposed betrayal of President Donald Trump.
Conservative group Republicans for the Rule of Law are expected to run advertisements on major news outlets in the D.C. area beginning Thursday calling for witnesses to be allowed in President Donald Trump's impeachment trial.
The White House is trying to quash Bolton's disclosures, reportedly sending a letter to his attorney warning against publication of his new book.
Former Justice Department officials discussed the importance of witnesses during the Senate's impeachment trial in a new video.
"This is the end game," author Grant Stern wrote on Twitter.
The president tweeted that if he had listened to his former national security adviser, "we would likely be in World War Six."
Senator John Kennedy told Fox News host Sean Hannity there is "a lot of hysteria" about the potential testimony of President Donald Trump's former national security advisor.
Democrats and Republicans will submit—unsurprisingly—diametrically opposing questions to Chief Justice John Roberts, with most senators likely already decided what their final vote on removing the president from office will be.
"I've known him for two decades," Hannity said.
"I can't imagine that the President of the United States said that to him," Giuliani said.
Judge Andrew Napolitano denounced the GOP's newly formed criticism of former National Security Advisor John Bolton during a Tuesday appearance on Fox Business channel, while suggesting that Bolton was likely to be called to testify in the Senate trial of President Donald Trump.
Nancy Pelosi's daughter Christine Pelosi wonders whether John Bolton would testify, after he said that he believes Bolton.
Democrats' only hope to hear from the former national security adviser could be through his forthcoming book's manuscript.
"Executive privilege is a shield, not a sword, and cannot be relied upon to silence a former official like John Bolton if he is willing to testify," said Bradley Moss, a national security law expert.
Bolton left the administration under a cloud in September, but fresh details from his forthcoming book are now undermining Trump's impeachment defense.
Fox News host Tucker Carlson said that former National Security Advisor John Bolton deserved "humiliation" and was bitter over President Donald Trump blocking his attempts at launching a military conflict with Iran, after reports emerged that Bolton's upcoming book confirms a key impeachment claim.
Lou Dobbs said on his Fox Business program Monday that former National Security Adviser John Bolton had become a "tool for radical Dimms and the Deep State" because Bolton's literary agency, Javelin, had also published books by former members of the Trump administration.
"If John Bolton says it," Collins said, "It must be true. Even though the president said it didn't happen."
Chris Wallace suggests that the news of Bolton's book had the potential to change how the president's impeachment trial proceeds.
No one should doubt Bolton's attention to detail—and his appetite for bureaucratic score-keeping.
Just two GOP senators were exceptions—Mitt Romney and Susan Collins—both of whom signaled before the Bolton revelations they'll side with Democrats to subpoena witnesses and documents.
"It's pretty fair to say that John Bolton has a relevant testimony to provide," the Republican senator told reporters.
"To support Ukraine is to support a rules-based international order that enabled major powers in Europe to avoid war for seven decades," William Taylor wrote.
Obama-era appointee Joyce Vance said a tweet denying the claims wasn't "enough" as Bolton was willing to testify.
"The Democrat controlled House never even asked John Bolton to testify. It is up to them, not up to the Senate!" Trump tweeted on Monday.