On early Monday morning, President Donald Trump denied former National Security Adviser John Bolton’s bombshell allegation that he directly connected aid to Ukraine to his push for Ukrainian officials to help his efforts to have Joe Biden investigated.

According to an unpublished manuscript of Bolton’s upcoming book obtained by the New York Times, Trump told Bolton last August that he would not release the $391 million in military aid to Ukraine until Ukrainian government officials had given him, in the Times’ words, “all materials they had about the Russia investigation that related to” Biden and Hillary Clinton.

Trump vehemently denied Bolton’s account after the Times published its report.

“I NEVER told John Bolton that the aid to Ukraine was tied to investigations into Democrats, including the Bidens,” Trump tweeted shortly after midnight. “In fact, he never complained about this at the time of his very public termination. If John Bolton said this, it was only to sell a book.”

Trump claimed the White House’s memo of his call with Ukrainian President Volodymr Zelensky in July is “all the proof that is needed.”

Bolton’s manuscript included explosive accounts of other Trump administration officials’ involvement or knowledge of the scheme, such as his allegation that he had told Attorney General Bill Barr he was concerned about Trump lawyer Rudy Giuliani’s operations in Ukraine.

Bolton also wrote that Secretary of State Mike Pompeo privately admitted Giuliani’s smears of former Ambassador to Ukraine Marie Yovanovitch were groundless, according to the Times.

Pompeo also believed Giuliani’s mudslinging was for the benefit of his clients, according to the ex-national security adviser.

Additionally, Bolton alleged that acting White House Chief of Staff Mulvaney was present during at least one of Trump’s calls with Giuliani in which they discussed Yovanovitch.

Charles J. Cooper, Bolton’s lawyer, told the Times that he had given the White House a copy of the book on December 30 to ensure it did not contain classified information. He said the review process had been “corrupted” by whoever had leaked the manuscript to the outlet.

Bolton said in early January that he would agree to testify in the Senate impeachment trial of Trump if he were subpoenaed. However, Senate Republicans have rejected Senate Minority Leader Chuck Schumer’s (D-NY) efforts to include new witnesses and documents in the trial, which began last week.

Schumer seized on the Times’ report, emphasizing the importance of having Bolton and other top administration officials testify.

“John Bolton has the evidence,” Schumer tweeted on Sunday evening. “It’s up to four Senate Republicans to ensure that John Bolton, Mick Mulvaney, and the others with direct knowledge of President Trump’s actions testify in the Senate trial.”

The House impeachment managers and Speaker Nancy Pelosi (D-CA) said Bolton’s account “confirms what we already know.”

“There can be no doubt now that Mr. Bolton directly contradicts the heart of the President’s defense and therefore must be called as a witness at the impeachment trial of President Trump,” they said in a statement.