Donald Trump has been accused of trying to silence John Bolton’s alleged revelations about the Ukraine affair, by claiming material contained in a draft manuscript is “classified”.

The White House informed the former national security adviser that his manuscript, scheduled to be published in March, appeared to contain “significant amounts of classified information“ and could not be published in its current form.

A letter from the national security council to Bolton’s attorney, Charles Cooper, said the manuscript contained some material that was considered “TOP SECRET”.

“Under federal law and the nondisclosure agreements your client signed as a condition for gaining access to classified information, the manuscript may not be published or otherwise disclosed without the deletion of this classified information,” it added.

Yet there was immediately criticism that the White House was trying to silence Mr Bolton, whose claims about what the president told him to do about Ukraine, have hit hard with some Republicans.

All the president's lawyers: The team fighting Trump's impeachment Show all 6 1 /6 All the president's lawyers: The team fighting Trump's impeachment All the president's lawyers: The team fighting Trump's impeachment Alan Dershowitz Dershowitz is a controversial American lawyer best known for the high-profile clients he has successfully defended. Those clients have included OJ Simpson, Jeffrey Epstein and Harvey Weinstein. One longtime Harvard Law associated told the New Yorker Dershowitz "revels in taking positions that ultimately are not just controversial but pretty close to indefensible." Getty All the president's lawyers: The team fighting Trump's impeachment Ken Starr Starr became a household name in the 1990s as the independent counsel who led the investigation that led to Bill Clinton's impeachment. That investigation began as a look into a real estate scandal known as Whitewater, and eventually led to impeachment after Mr Clinton lied under oath about having an affair with White House intern Monica Lewinsky. AP All the president's lawyers: The team fighting Trump's impeachment Jay Sekulow Sekulow is the president's longtime personal attorney, and, now, personal lawyer in the White House. He has been accused by former Rudy Giuliani associate Lev Parnas of being "in the loop" during the Ukraine scandal. Getty All the president's lawyers: The team fighting Trump's impeachment Pam Bondi Bondi is the former attorney general in Florida, and a longtime backer of the president's. She made a name for herself in Florida for taking hyper partisan stances on issues, and her penchant for publicity. She is likely to be a prominent public-facing figure during the trial. AFP/Getty All the president's lawyers: The team fighting Trump's impeachment Pat Cipollone Cipollone is the White House counsel, and leading the president's defence team. Getty All the president's lawyers: The team fighting Trump's impeachment Rudy Giuliani While not officially named as one of the president's impeachment lawyers, it is hard to ignore Giuliani's outsized role in this process. The former mayor of New York has been making headlines for months as he defends his client, and for his apparent role in the effort to compel Ukraine to launch the investigation into Joe Biden. We'll see how he figures in the actual trial, which he has said he would like to be a part of. Reuters

As a result, it now appears Mr Trump’s impeachment trial in the Senate will feature some witnesses, potentially including Mr Bolton, who has said he would testify if subpoenaed to do so.

John Bromwich, a layer and federal prosecutor who served as inspector general of the department justice from 1994 to 1999, accused the administration of deliberately seeking to halt or delay the publication of Mr Bolton’s booked, due to be titled The Room Where It Happened.

“The idea that Bolton would draft a manuscript that contains “significant amounts of classified information” is ridiculous,” he wrote on Twitter.

“He knows what’s classified and what’s not. This is tampering with the pre-publication process to intimidate and achieve political ends.”

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On Sunday, the New York Times revealed that in the document being vetted by the White House – a standard procedure for books by former officials – Mr Bolton claimed Mr Trump had told him last August he wanted to continue to freeze around $400m in military aid to Ukraine.

He said the money, assigned by Congress to help Ukraine confront aggression from Moscow, would only be released once the authorities in Kiev announced an investigation into Joe Biden and his son. This so-called “quid pro quo” is at the very heart of the impeachment case against Mr Trump.

In its report about the book on Sunday, the newspaper noted the White House could use the vetting process “to delay or even kill the book’s publication or omit key passages”.

Reaction to the existence of Mr Bolton’s manuscript with swift and explosive.

“John Bolton has the evidence,” tweeted Chuck Scuhmer, the Democrats’ leader in the Senate, as the party doubled down on demands Mr Bolton and others be allowed to testify.

Democrats were joined by several key Republican senators, including Mitt Romney and Susan Collins, who indicated they supported hearing from witnesses about the allegations. Although Republicans control the Senate, Democrats would only need four members of the GOP to back their demand for witnesses.

Republican Senate leader Mitch McConnell, who has tried to block any witnesses and secure Mr Trump’s acquittal as rapidly as possible, informed Republican senators on Tuesday that the party “did not” have the enough to block testimony.