WASHINGTON — There was no filibuster for Clarence Thomas, whose Supreme Court confirmation hearings provoked a national uproar over sex, race and the behavior of powerful men.

Antonin Scalia, for a generation the court’s irrepressible conservative id, earned 98 votes in the Senate. Ruth Bader Ginsburg, now the patron saint of liberal jurisprudence, got 96.

But with the Senate careering toward a chamber-rattling showdown over President Trump’s nominee, Judge Neil M. Gorsuch, the body’s long history of relative collaboration on Supreme Court matters has come to this: Next week, the last bastion of comity is expected to fall over a plainly qualified, mild-mannered nominee who had no major stumbles in his hearings.

And each party’s justification can often be summarized with a schoolyard classic: They started it.

“I worry for the institution,” said Senator Susan Collins, Republican of Maine, who broke with her colleagues last year in calling for a hearing and a vote on Judge Merrick B. Garland, President Barack Obama’s own plainly qualified, mild-mannered nominee. “I think, at the risk of alienating everyone I have to work with here, that there’s real shortsightedness on both parts.”