The Republican leader unified his caucus by relying on precedent
"Clinton's trial was divided into pieces. The Senate agreed unanimously to begin with a briefing, opening arguments, questions from senators, and a vote to dismiss. Whether to hear witnesses or introduce additional evidence were questions decided later. "That was the unanimous bipartisan precedent from 1999," McConnell said. "Put first things first, lay the bipartisan groundwork, and leave mid-trial questions to the middle of the trial."
"The arrangement satisfied Chuck Schumer back when he was a recently elected junior senator from New York. Funny how times change. Now Senate minority leader, and looking to damage Republicans in a presidential election year, Schumer demanded that McConnell call witnesses and ask for additional documents at the outset of the proceedings. Pelosi followed his cues. After the House impeached Trump on December 18, she said she wouldn't transmit the articles of impeachment until McConnell gave in to Schumer's demands.
"McConnell refused. He continued to point to the (relative) bipartisanship of the Clinton era. "The Senate said, 100 to nothing, that was good enough for President Clinton," he said on January 6. "So it ought to be good enough for President Trump. Fair is fair." The following day, McConnell ridiculed the idea that Pelosi had "leverage" over the Senate: "Apparently this is their proposition: If the Senate does not agree to break with our own unanimous bipartisan precedent from 1999, and agree to let Speaker Pelosi hand-design a different procedure for this Senate trial, then they might never dump this mess in our lap." Fine with him. The Senate has plenty of other things to do." . . .