Mr Trump took to Twitter to lash out at Mr Bolton, whom he sacked last September, after a draft of his upcoming book, in which he challenged the Republican leader’s defence, was leaked to the press. The emergence of the explosive allegations which came to light on Sunday was seen as a game-changer in the historic impeachment trial. In response, Democrats ramped up their drive to call witnesses to the Senate.
Senate Majority Leader Mitch McConnell, a Republican, has said his party lacked the votes to block impeachment witnesses, Fox News reports.
Mr Bolton and Mike Pompeo, the US Secretary of State, are some of the names being mentioned as potential witnesses.
Republican Mitt Romney said it would be “important to hear from John Bolton for us to make an impartial judgement”.
In order for the vote to pass it would need the backing of four Republicans along with all 47 Democrats and independents.
At the moment, it looks like at least two of the 53 Republicans in the Senate could potentially swing that way.
If three Republicans voted with the Democrats it would result in a tie.
Mr Bolton’s book, The Room Where It Happened: A White House Memoir, is due to be released in March.
Mr Trump had clashed with Mr Bolton over how the US dealt with Iran, North Korea and Afghanistan before he ousted him as national security adviser.
READ MORE: Impeachment timetable: Schedule as Senate continues impeachment trial
A senior Democrat aide denied his party had collaborated with Mr Bolton to dig up dirt on the president.
“We’ve had no communication with Mr Bolton or Mr Bolton’s lawyers,” said the aide.
Republican senator Rick Scott, who represents the swing state of Florida, compared the emergence of the Bolton information to what happened when Brett Kavanaugh was awaiting confirmation to the Supreme Court in 2018.
Christine Blasey Ford came forward alleging she had been sexually assaulted by Judge Kavanaugh during their teenage years.
Mr Kavanaugh strongly denied the claims and was later confirmed to the country’s highest court.
Mr Scott told Fox News his opponents are clutching at straws in a bid to drag the impeachment trial out for as long as possible.
He said: “This will never end. This is just like Kavanaugh.
“The Democrats are going to come up with something new every day to keep this going on forever.”
The Senate is expected to acquit President Trump but allowing witnesses such as Mr Bolton could inflict political damage on the Republican president as he seeks re-election on November 3.