Senate GOP Leader Mitch McConnell will vote to acquit former President Donald Trump in his second impeachment trial, Fox News has learned, as day five of the trial is now underway.

McConnell's vote had been closely watched since he's been very critical of Trump's role in inciting the Jan. 6 riot, and his wife -- former Transportation Secretary Elaine Chao -- resigned from the administration in the aftermath of the attack that left at least five people dead, including a Capitol Police officer.

In a speech on Jan. 19, McConnell, R-Ky., said Trump "provoked" the mob that tried to use "fear and violence" to stop the joint session of Congress from certifying then-President-elect Biden's win on Jan. 6.

VOTE ON CONVICTION COULD COME SATURDAY AS IMPEACHMENT TRIAL ARGUMENTS AND SENATORS' QUESTIONS CONCLUDE

"The mob was fed lies," McConnell at the time. "They were provoked by the president and other powerful people."

McConnell alerted colleagues of his decision Saturday morning via email before the Senate convened for what could have been the final day of Trump's trial for "incitement of insurrection."

McConnell gave an early signal of where he stood when he joined the majority of Republican senators earlier this week to vote that the trial was unconstitutional because Trump is no longer president. In that vote, just six GOP senators joined with Democrats to allow the trial to proceed.

DAY FOUR: TRUMP'S IMPEACHMENT DEFENSE RESTS AFTER THREE HOURS: 'THERE WAS NO INSURRECTION'

Conviction was always going to be an uphill climb, since 17 GOP senators would need to join all 50 Democrats to meet the supermajority threshold. If McConnell had decided to vote to convict he may have brought more of his colleagues over, but without his support, Trump is all-but-certain headed for a second acquittal. 

McConnell voted once before to acquit Trump in his first impeachment trial a year ago related to abuse of power and obstruction of Congress.