The team around U.S. President Donald Trump is turning against his former national security adviser after John Bolton, in an upcoming book, undercuts one of the key points of the president’s defence in his impeachment trial.

A senior legal adviser to the Trump re-election campaign, Jenna Ellis, who is also an attorney to the president, accuses Bolton of “willing to sell out America…just to score a book deal or 5 minutes of fame.”

Retweeting Ellis on Monday, the White House Press Secretary, Stephanie Grisham, said this was “So true & so unfortunate.”

So true, & so unfortunate. But it’s OK because @realDonaldTrump did nothing wrong, & is undeterred as always. He continues to work on behalf of this country, & most importantly - produce real results that benefit Americans & their families at Stephanie Grisham (@PressSec) January 27, 2020.

While Trump was hosting Israeli Prime Minister Benjamin Netanyahu at the White House on Monday, he was asked by a reporter about the key allegation in Bolton's book.

The president responded that "nothing was ever said to John Bolton" and that what is written in the book is "false."

At least a senator of Trump’s Republican party is indicating the revelations in the book may compel witnesses, including Bolton, to be called at the impeachment trial.

Senator Mitt Romney of the State of Utah says the former national security adviser has relevant testimony to provide, and he thinks “it’s increasingly likely that other Republicans will join those of us who think we should hear from John Bolton.”

Trump’s defence team has maintained that President had valid reasons for withholding military aid from Ukraine.

In their arguments to senators, the President’s lawyers are rebutting Democrats’ allegation of a “quid pro quo.”

They say the president was not going to help Kyiv until Ukrainian President Volodmyr Zelensky announced an investigation of former U.S. Vice President Joe Biden and his son who served on the board of Burisma, a Ukrainian energy company, while his father was in office.

Bolton, in “The Room Where It Happened: A White House Memoir,” to be published March 17, states Trump wanted to freeze military assistance to Ukraine until Kyiv’s government announced the investigation.

The New York Times, which revealed online Sunday excerpts from the book, also reported after Trump’s July 25, 2019, phone call with Zelensky, Bolton raised his concerned with Attorney General William Barr that the president’s personal attorney, Rudy Giuliani, was pursuing a shadow Ukraine policy.

Trump, early Monday morning, denied Bolton’s account, saying his former adviser “never complained about this at the time of his very public termination. If John Bolton said this, it was only to sell a book.”

“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,… at Donald J. Trump (@realDonaldTrump) January 27, 2020.

The president later inaccurately stated in a tweet that Democrats never asked Bolton to testify during last night’s impeachment inquiry in the House.

Contents of Bolton’s manuscript were submitted to the National Security Council for a standard security review on December 30, 2019.

Bolton’s attorney, Charles Cooper, is blaming the White House for disclosing contents of the book.

Before Bolton spent 17 months as Trump’s national security adviser, he had a long track record as a hawk on foreign policy, giving him credibility among Republican senators who will have to decide if he should testify in the ongoing impeachment trial. (VOA)

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