Former National Security Advisor John Bolton told an audience at Vanderbilt University on Wednesday night that his testimony in President Trump's impeachment proceedings would have had no impact on the outcome of the trial, despite assurances from Congressional Democrats of game-changing revelations based on leaked sections of his upcoming book.

"People can argue about what I should have said and what I should have done," said Bolton, adding "I will bet you a dollar right here and now my testimony would have made no difference to the ultimate outcome."

"I sleep at night because I have followed my conscience," he said.

His predecessor, Susan Rice, pushed back - suggesting that his decision to remain silent during the impeachment process was "inconceivable" despite never having been subpoenaed, according to The Federalist.

"It’s inconceivable to me that if I had firsthand knowledge of a gross abuse of presidential power, that I would withhold my testimony," Rice said, adding "I would feel like I was shamefully violating my oath that I took to support and defend the Constitution."

Bolton argued that the House botched the process and condemned House Democrats for having committed “impeachment malpractice.” “The process drove Republicans who might have voted for impeachment away from the president because it was so partisan,” Bolton claimed. Bolton’s new book, “The Room Where It Happened: A White House Memoir,” is slated to be released next month is expected to reveal what Bolton might have said had he been forced to testify before lawmakers in the impeachment proceedings. Republicans in the Senate defeated Democrats’ efforts to bring Bolton before the upper chamber before the final vote with only Sens. Mitt Romney of Utah and Susan Collins of Maine voting in favor of the measure. -The Federalist

Sections of Bolton's book infamously leaked to the New York Times at the 11th hour of Trump's impeachment, in which he accuses the president of tying nearly $400 million in military aid to Ukraine to investigations he wanted into former Vice President Joe Biden and his son Hunter, as well as whether Ukraine's previous administration meddled in the 2016 US election.