It would be nice to have faith that, as the Senate prepares to receive the articles of impeachment against President Trump and gears up for its role in this rare and momentous process, it will do the right thing. Confronted with a mountain of evidence that an American president abused his power by shaking down a vulnerable country for his own personal gain — and then stonewalled a congressional investigation into his behavior — senators should spare no effort in conducting a fair and thorough trial, complete with witnesses and documentary evidence.

Alas, in 2020, the Senate is led by Mitch McConnell, who has demonstrated time and again that he is more concerned with covering for Mr. Trump than protecting the integrity of the office Mr. Trump holds, the security of the nation he leads or the Constitution he swore to defend.

With few exceptions, Mr. McConnell has enjoyed the lock-step support of his caucus. So it has been notable to hear over the past few days a hint of dissension within the ranks, as a handful of Republican senators, including Lamar Alexander of Tennessee, have indicated that they oppose a straight-up dismissal of the charges against the president.

“I think we should hear the case. We have a constitutional duty to do that,” Mr. Alexander said.

This is a low bar to clear: The House of Representatives marshaled extensive and damning testimony against Mr. Trump, despite his best efforts to keep it from coming out. The debate now should be how to get the fullest possible account of the Ukraine scandal, not whether you need more than one hand to count the number of Republicans who are willing to take up the case at all.