Washington(CNN) Former national security adviser John Bolton, who has been a central figure in Democrats' fight to hear from witnesses in the Senate trial, defended on Thursday Trump administration officials who testified as part of the House impeachment inquiry.
"All of them acted in the best interest of the country as they saw it and consistent to what they thought our policies were," Bolton said during a private event in Austin, Texas, according to CNN affiliate KXAN.
His comments came a day before the Senate votes Friday on whether to seek additional witnesses, including whether to hear from Bolton about his explosive allegation in the Ukraine scandal. It became clearer on Thursday night that the Senate trial is all but certain to come to a swift end without hearing from witnesses or subpoenaing documents.
Bolton said members of the Trump administration should "feel they're able to speak their minds without retribution."
"The idea that somehow testifying to what you think is true is destructive to the system of government we have, I think, is very nearly the reverse -- the exact reverse of the truth," he said.
Bolton has said he's willing to testify in the Senate trial if he is subpoenaed. The House had sought his testimony but ultimately never subpoenaed Bolton.
In his forthcoming book, Bolton alleges that Trump told him over the summer that he wanted to continue holding military aid to Ukraine until the country helped with investigations into his potential political opponents, according to a draft manuscript first reported by The New York Times. A source with direct knowledge of the manuscript has told CNN the Times' telling of Bolton's discussion with Trump is accurate.
On Wednesday, Trump attacked Bolton on Twitter and claimed his forthcoming book is "nasty and untrue."
The administration has repeatedly cited national security concerns as to why they would not want Bolton and other current and former administration officials to testify in the Senate trial.
Senate Majority Leader Mitch McConnell has argued that allowing witnesses would lead to an indefinite delay in the trial, prompt executive privilege concerns and have no impact on the outcome of the trial.