Business Insider reports Senate Majority Leader Mitch McConnell made a shocker announcement on Tuesday.
He said the GOP hasn't secured the votes necessary to block Democrats from calling witnesses to testify in the impeachment trial.
Pressure on Republicans has intensified after a bombshell report was published by The New York Times on Sunday.
John Bolton allegedly writes in his new book that President Donald Trump said he'd withhold military aid to Ukraine until the country investigated his political rivals.
McConnell reportedly compiled a list of "yes," "no," and "maybe" votes, but didn't show the whip count to his fellow senators.
But Republican leadership is reportedly confident it can win over the necessary GOP votes by Friday.
The party is arguing that calling witnesses would extend the trial indefinitely.