WASHINGTON — Before the election, it was clear that Democrats were looking at the very real prospect of scrapping the filibuster to keep Republicans from blocking the Supreme Court nominees of a President Hillary Clinton.

Now the tables are turned. It is the Republicans who will control the White House, Senate and House — the coveted Washington trifecta. And that raises a crucial question: If Democrats in the even more narrowly divided Senate embrace the filibuster to block what could be a flood of legislation, would Republicans respond by eliminating the 60-vote threshold in order to push their priorities through on simple majority votes?

In the afterglow of their election success, Republicans prefer not to discuss this unpleasant possibility. They would rather rhapsodize about a sunny legislative future in which the two parties work in harmony, negating the need for all those troublesome Senate cloture votes to try to break filibusters (a tactic that they, in fact, employed very effectively to stymie President Obama).

“I think what the American people are looking for is results,” Senator Mitch McConnell of Kentucky, who will retain his majority leader title by virtue of surprising Republican victories, told reporters. “And to get results in the Senate, as all of you know, it requires some Democratic participation and cooperation.”