Senate Majority Leader Mitch McConnell has signed onto a measure that would allow lawmakers to begin President Trump’s impeachment trial without receiving the articles House Speaker Nancy Pelosi is withholding.

McConnell, a Kentucky Republican, is among more than one dozen Republicans who are co-sponsors of a measure authored by Sen. Josh Hawley, a Missouri Republican, authorizing the Senate to begin the trial as early as Monday, or 25 days after the House passed the impeachment articles on Dec. 19.

The measure would require a change to the Senate rules, which is normally authorized with an affirmative vote from 67 senators. A top aide signaled McConnell isn’t going to “go nuclear” and allow a rules change to pass with only 51 votes, so the measure probably cannot pass.

A vote has not been scheduled, but it would put Democrats on the spot.

Several of them have called on Pelosi to send over the articles or have indicated they are ready to start the trial, which was supposed to begin this week. The California Democrat is holding onto the articles, she said, until McConnell provides the details of a resolution that will govern the terms of a Senate trial. Democrats want key Trump administration officials to testify and held off on sending the articles in an effort to pressure McConnell to agree to a witness list before the trial begins.

McConnell has rejected their request.

He chided House Democrats Thursday for failing to send over the articles, noting the impatience among their Democratic colleagues in the Senate.

"The speaker of the House has managed to do the impossible," McConnell said. "She has created this growing bipartisan unity in the United States Senate in opposition to her own reckless behavior."

Democrats say Republicans are trying to avoid testimony that could incriminate the president by refusing to agree to a witness list ahead of the trial.