Washington (CNN) President Donald Trump in August told his then-national security adviser John Bolton that he wanted to continue holding military aid to Ukraine until the country helped with investigations into Democrats -- including former Vice President Joe Biden -- the New York Times reported Sunday, citing multiple people's descriptions of an unpublished draft manuscript by Bolton.

A source with direct knowledge of the manuscript told CNN the New York Times' telling of Bolton's account of the Ukraine aid hold discussion with Trump is accurate.

Trump's purported statement, as described by Bolton, would directly tie the US military aid freeze with the President's requests that Ukraine announce investigations into his political rivals -- undermining a key pillar of the President's impeachment defense that the two circumstances are unrelated.

There is no evidence of wrongdoing by either Joe Biden or his son, Hunter Biden, in Ukraine, and Joe Biden has repeatedly defended his son and himself.

In a series of late night tweets, Trump denied claims he told Bolton aid to Ukraine was tied to an investigation of the Bidens. "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," Trump tweeted

Bolton spokeswoman Sarah Tinsley said the draft of the book "was transmitted to the White House for pre-publication review by the National Security Council."

As for the claim in the New York Times that Bolton has circulated a draft manuscript to his close aides, Tinsley said, "The ambassador has not passed the draft manuscript to anyone. Period." Tinsley declined to comment on the contents of the book manuscript.

Later Sunday night after The New York Times report was published, a page for the upcoming book was posted by the publisher, Simon & Schuster, and it was available for pre-order on Amazon.

Revelations about the contents of Bolton's manuscript draft are likely to heighten calls from Democrats for Bolton to testify in the ongoing Senate impeachment trial. Bolton has said he would give testimony if he's subpoenaed.

Bolton attorney claims draft manuscript was improperly accessed

Bolton's attorney Charles Cooper submitted a draft manuscript of the forthcoming book to the National Security Council on December 30, 2019, he said in a statement Sunday.

Cooper said he submitted the manuscript on Bolton's behalf despite "our firm belief that the manuscript contained no information that could reasonably be considered classified."

Cooper also comes close to confirming the accuracy of the Times report, alleging that the "prepublication review process has been corrupted" and that "information has been disclosed by persons other than those properly involved in reviewing the manuscript."

Bolton's attorney also provided CNN with a copy of the letter he sent to the National Security Council's senior director for records management. In the letter, Cooper suggests that the NSC official assured him that "the sole purpose of prepublication security review is to ensure that SCI or other classified information is not publicly disclosed."

Cooper provided the manuscript to NSC with the understanding that "the process of reviewing submitted materials is restricted to those career government officials and employees regularly charged with responsibility for such reviews."

Democrats weigh in

In a joint statement Sunday night reacting to the Times' report, the seven House impeachment managers said the revelations confirm "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," the statement said, adding "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 House managers added: "Americans know that a fair trial must include both the documents and witnesses blocked by the President — that starts with Mr. Bolton."

Other congressional Democrats are also demanding that Bolton testify in the Senate impeachment trial.

"Amb. Bolton reportedly heard directly from Trump that aid for Ukraine was tied to political investigations. The refusal of the Senate to call for him, other relevant witnesses, and documents is now even more indefensible. The choice is clear: our Constitution, or a cover-up," House Speaker Nancy Pelosi tweeted.

Senate Minority Leader Chuck Schumer echoed the house speaker's sentiments, tweeting, "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."

Bolton purportedly implicates others in Trump's orbit

In the draft book manuscript, Bolton describes how the Ukraine scandal developed in his final months in the White House, including new details about different senior administration officials' involvement, according to the Times.

This includes an account of Secretary of State Mike Pompeo acknowledging privately that claims made by Trump's personal lawyer Rudy Giuliani about then ambassador to Ukraine Marie Yovanovitch being corrupt had no basis, according to the Times.

The newspaper also reported that Bolton claims Pompeo believed Giuliani might have been acting on behalf of his private clients in his push to oust Yovanovitch. On a flight from Palm Beach to LaGuardia Sunday night, Giuliani told CNN this was "absolutely wrong," adding that Yovanovitch's removal was an "absolutely justifiable act."

Giuliani asserted Bolton is going to be "very embarrassed" when more details come out about corruption in Ukraine and Bolton's decision not to do anything about it during his time in office.

The Times also reports that Bolton wrote in the draft that acting White House Chief of Staff Mick Mulvaney was present during at least one phone call where Giuliani and Trump discussed Yovanovitch.

Bolton also claims in his draft manuscript, according to the paper, that he told Attorney General Bill Barr that Trump had mentioned him during his July 25 call with Ukrainian President Volodymyr Zelensky. A Justice Department official, however, told CNN that while Barr and Bolton spoke in the days after the call, Bolton didn't mention the Ukraine call or the fact Barr's name has been mentioned.

This story has been updated with additional developments.