Former national security adviser John Bolton reportedly wrote in an outline for a book that President Donald Trump tied the withheld Ukraine aid to the country’s announcement that it would investigate former Vice President Joe Biden and his son Hunter.

Drafts of the book outline obtained by The New York Times describe Trump telling Bolton in August that he wanted to continue freezing nearly $400 million in congressionally approved military assistance to Ukraine until officials there agreed to help investigate his political rival.

SCOOP: Bolton book draft, circulated to associates and sent to WH for review process, describes a convo w POTUS where he says he doesn't want to release withheld aid till Ukraine turned over material related to investigations @nytmike and me https://t.co/N3Tsce4gR7 — Maggie Haberman (@maggieNYT) January 26, 2020

Trump denied Bolton’s reported account in a tweet Sunday night, and insisted he “never” told Bolton the Ukraine aid was tied to “investigations into Democrats.” The president also said Bolton “never complained about this,” apparently referring to freezing the military aid.

I NEVER told John Bolton that the aid to Ukraine was tied to investigations into Democrats, including the Bidens. 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. With that being said, the... — Donald J. Trump (@realDonaldTrump) January 27, 2020

A key part of Trump’s defense in the impeachment process has been that his decision to withhold the aid was completely separate from his request for Ukraine to investigate the Bidens. Tying the two together would indicate that Trump attempted a quid pro quo with a foreign government in order to sway the 2020 presidential election ― which Democrats have said was the case since the impeachment inquiry began.

According to the Times, Bolton alleged that Secretary of State Mike Pompeo privately admitted there was no basis to Rudy Giuliani’s claims that ousted U.S. ambassador to Ukraine Marie Yovanovitch was corrupt, and he believed Trump’s personal attorney was acting on behalf of other clients.

Bolton also wrote that acting White House chief of staff Mick Mulvaney was around for at least one phone call during which Trump and Giuliani discussed Yovanovitch, according to the Times.

Bolton also reportedly said he raised his concerns about Giuliani’s shadow diplomacy with Attorney General William Barr after Trump’s July phone call with Ukrainian President Volodymyr Zelensky. Bolton alleged that he was the one who informed Barr that the president mentioned him on the call, according to the Times. A spokesperson for Barr told the publication he denied that allegation.

Bolton’s account of Trump’s alleged remarks were included in the former national security adviser’s unpublished manuscript, which he has been circulating to close associates. The book, according to the Times, represents what Bolton might say in a testimony if the Senate calls him as a witness in Trump’s impeachment trial.

Bolton spox Sarah Tinsley tells @HouseInSession: "The ambassador transmitted a hard-copy draft of his manuscript to the White House for pre-publication review by the National Security Council. The ambassador has not passed the manuscript to anyone else, only the NSC.” https://t.co/Hn2FnyfZ7Z — Jordan Fabian (@Jordanfabian) January 27, 2020

“John Bolton has the evidence,” Schumer tweeted Sunday night. “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.”

John Bolton has the evidence.



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.https://t.co/JbazBaYdRU — Chuck Schumer (@SenSchumer) January 26, 2020

The Democratic House impeachment managers also released a statement regarding the Times report.

“There is no defensible reason to wait until his book is published, when the information he has to offer is critical to the most important decision Senators must now make ― whether to convict the President of impeachable offenses,” the statement read.

The trial for Trump, who the House impeached in December, began earlier this month. House impeachment managers spent three days last week presenting their opening arguments to senators, while Trump’s defense team spent a short time on Saturday presenting their side. It’s unclear if the Senate will follow through with calling witnesses before voting on whether to remove the president from office.