The senators' comments came after The New York Times reported that, in an unpublished manuscript circulated in recent weeks, Bolton said Trump told him he wanted to continue to hold hundreds of millions of dollars in aid for Ukraine until prosecutors in the country agreed to announce an investigation into his Democratic rivals, including former Vice President and 2020 presidential hopeful Joe Biden.
In a tweet posted early Monday, Trump denied Bolton's claim.
"I NEVER told John Bolton that the aid to Ukraine was tied to investigations into Democrats, including the Bidens," the president wrote. "If John Bolton said this, it was only to sell a book."
Bolton has previously signaled his willingness to appear before the Senate to testify as part of Trump's impeachment trial, however, it was not immediately clear whether there would be enough support from Republicans to call witnesses. He wants to testify for several reasons, including fears that he could be accused of not speaking up before the release of his book in order to boost sales, The Times reported, citing his unnamed associates.
Bolton had been asked to testify last year as part of the House impeachment inquiry but he and his former deputy, Charles Kupperman, declined and asked a court to clarify whether they were legally required to appear. Trump had earlier ordered White House officials not to cooperate with the inquiry, which he framed as illegitimate.
Democrats launched the impeachment inquiry after learning of a whistleblower complaint filed in August by an official concerned over Trump’s attempts to get Ukrainian officials to investigate Biden.
Trump has denied any wrongdoing.
In a closed-door interview with lawmakers in October, Fiona Hill, a former White House adviser on Russia, testified Bolton was so disquieted by back channel Ukraine activities that he referred to Trump’s personal attorney, Rudy Giuliani, as a “hand grenade who is going to blow everybody up.”
The Associated Press contributed to this report.