She did thank Mr. Grassley for overseeing the hearings fairly.

Ms. Feinstein also reminded the public about the treatment last year of Judge Merrick B. Garland, President Barack Obama’s nominee for the seat left by Justice Antonin Scalia, who died in February 2016. Republicans refused to even consider Judge Garland during a presidential election year.

“In my view, this is not a routine nomination,” she said at the top of her remarks.

In his own comments, Mr. Grassley expressed no regrets. “I believe then and I believe now that we took the right course for the Senate and for the court,” he said.

Leahy laments a tarnished institution.

From the hearing’s opening moments, lawmakers took turns lamenting the state of the Senate, holding forth on the present divisions but appearing resigned to the institutional upheaval that awaits this week.

Few sounded as aggrieved as Senator Patrick J. Leahy, Democrat of Vermont and the body’s longest-serving member.

He first suggested that Republicans’ treatment of Judge Garland last year had convinced Judge Gorsuch that “this committee is nothing more than a partisan rubber stamp,” allowing the nominee to evade straightforward questions during his hearings.

He said that Senator Mitch McConnell of Kentucky, the Republican majority leader, had “promised to use whatever tactic is necessary to get his way, to make sure that Donald Trump’s nominee is confirmed, even if that means forever damaging the United States Senate.”