Democrats, conceding that they did not have the power to stop it, unleashed a torrent of anger and parliamentary tactics intended to disrupt Senate business. They accused Republicans of gross hypocrisy, pointing to their refusal in early 2016 to consider Merrick B. Garland, President Barack Obama’s nominee to fill a Supreme Court vacancy, because it was an election year.
“We can’t have business as usual when Republicans are destroying the institution, as they have done,” said Senator Chuck Schumer, Democrat of New York and the minority leader.
But Republicans were unapologetic. In the four years since Mr. Trump took office, they have rarely parted ways with him, terrified of drawing a presidential rebuke on Twitter, unwilling to alienate his enthusiastic supporters who comprise a crucial section of the party’s base and worried about a backlash that could cost them their seats.
They were not about to start when it came to a lifetime appointment to the Supreme Court, a galvanizing issue for Republicans, especially socially conservative and religious Christian voters turned off by Mr. Trump’s persona.
“God created Republicans to do three things, and really only three things: cut taxes, kill foreign enemies and confirm right-facing judges,” said Brad Todd, a Republican strategist working for two of the party’s most endangered incumbents: Senators Thom Tillis of North Carolina and Cory Gardner of Colorado. “Only confirming judges has the potential to unite socially conservative populists and squishy corporatists with equal enthusiasm.”
Rick Santorum, a former senator from Pennsylvania and a prominent social conservative, recalled on Tuesday that he had initially demurred when Mr. Trump asked for his endorsement in 2016 because of what he called “character flaws.” But he changed course after Mr. Trump released a list of conservative possible Supreme Court picks.
“That’s how a lot of folks like me felt about the Trump presidency,” Mr. Santorum said.
Four years later, it has paid dividends. He called filling a third Supreme Court seat a “trifecta.”