Media caption Trump impeachment trial: Five possible twists ahead
Democrats have intensified their calls for former US National Security Adviser John Bolton to testify in President Donald Trump’s impeachment trial.
The pressure has grown following the report of a potentially explosive claim Bolton is said to make in a new book.
The New York Times cited a leaked Bolton manuscript as saying that Trump told him he wanted to freeze aid to Ukraine until Kyiv helped with investigations against the Democrats, including former Vice-President Joe Biden.
The US president rejected the report, which could undercut his denials that he had corrupt motives in asking Ukrainian President Volodomyr Zelensky in a phone call last July to investigate Biden, who is Trump’s potential White House rival.
Bolton, a Republican, is an unlikely hero for Democrats. Still, they believe he will act as a star witness, one who will provide irrefutable evidence of wrongdoing by Trump and help bolster the case for his removal from office.
Democrats once invested similar hopes in another Washington figure, Robert Mueller, the former special counsel.
But Mueller looked miserable while testifying in May about his Russian investigation, and did not change many people minds about the president.
Bolton could be different – or so Democrats hope.
Yale-educated Bolton, , was national security adviser from – .
He was “personally involved” in the president’s dealings with the Ukrainian officials, according to Bolton’s lawyer .
The former national security adviser was “at the nerve center for all important decisions”, says Matthew Spence , a former deputy assistant secretary of defense.
If Bolton were to testify, he would be able to provide the most detailed account to date of the president’s alleged political pressure on President Zelensky and the decision to freeze nearly $ (m) £ 400 m) in security aid.
Other witnesses have alleged that Trump administration officials used the aid as a bargaining chip to prod the Ukrainians into investigating the Bidens.
But they have not linked Trump explicitly to the withholding of aid in exchange for an investigation, or shown that Trump personally directed the operations.
Democrats believe the former national security adviser could provide the smoking gun.