Had Democrats retained the power to block President Trump’s choice of Judge Brett M. Kavanaugh, he might have been forced to find a more consensus candidate. With the Republicans’ Senate majority smaller than it was in 2017, Senator Mitch McConnell, Republican of Kentucky and the majority leader, might not have found it as easy now to corral the votes to overrule a filibuster. The entire political atmosphere around the nomination would be transformed.

“I never understood the strategy,” Mr. Bennet said about the insistence by leading Democrats and their activist allies that the party must try to derail Mr. Gorsuch with a filibuster even though the chances of success were slight to nonexistent. “We achieved nothing by filibustering Judge Gorsuch except giving Mitch McConnell the opportunity to strip us of our ability to filibuster a nominee who will cause a dramatic shift in the balance of the court.”