WASHINGTON — In the days leading up to the vote on Judge Neil Gorsuch’s confirmation to the Supreme Court in spring 2017, Sen. Susan Collins approached Sen. Michael Bennet on the Senate floor with an urgent plea.

“Please, don’t do it this time,” Collins, R-Maine, said to Bennet, her Democratic colleague from Colorado.

“It” was the Democratic inclination to mount a filibuster against Gorsuch, potentially forcing a showdown that would end with a move by Republicans to change Senate practices and eliminate supermajority filibusters against Supreme Court nominees.

Some members of both parties thought that prompting the fight would be rash and dangerous since Gorsuch was simply replacing another conservative, Antonin Scalia. Invoking the nuclear option, they argued, could needlessly inflict new political damage on both the Senate and the court.

Centrist members in both parties held behind-the-scenes negotiations in hopes of avoiding that confrontation. But no deal came together, and Republicans went on to curb the filibuster and seat Gorsuch.

Now, as the Senate faces another court vacancy — one that could tilt the court’s ideological balance and cement a conservative majority — the Democrats have few tools to fight the nomination. A different outcome last year could have had a huge effect on the more consequential battle now taking shape.

Had Democrats retained the power to block President Donald Trump’s choice of Judge Brett Kavanaugh, he might have been forced to find a more consensus candidate. With the Republicans’ Senate majority smaller than it was in 2017, Sen. Mitch McConnell, R-Ky., 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,” Bennet said about the insistence by leading Democrats and their activist allies that the party must try to derail 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.”

Escalating clashes over judges have torn the Senate apart for years. The tension over Gorsuch was the culmination of a series of brutal partisan episodes. In 2013, Senate Democrats used a procedural maneuver to end Republican filibusters against a series of lower-court judicial nominations made by President Barack Obama. Then, in 2016, McConnell and Senate Republicans refused to have so much as a hearing on Obama’s nomination in March of Judge Merrick Garland to the Supreme Court.

That decision handed Trump a court vacancy to fill immediately upon taking office, and he quickly moved forward with Gorsuch, a conservative appeals court judge from Colorado. Senate Democrats were still seething over Garland’s treatment, while the party’s increasingly influential progressive wing wanted to draw a hard line against Gorsuch and other nominees of the new administration. At one point, thousands protested outside the New York apartment of Sen. Chuck Schumer, the Democratic leader.

While most Democrats were digging in for a filibuster, discreet meetings and conversations were taking place among a handful of Senate Democrats and Republicans, including Bennet and Collins, as well as Sens. Chris Coons, D-Del.; John McCain, R-Ariz.; and a few others, along with their chiefs of staff.

The idea was to replicate an earlier approach by a bipartisan group of senators known as the Gang of 14, who banded together in 2006 to defuse a showdown over filibustering judicial nominees. (Collins and McCain were part of that group.)

The plan was to enlist enough Democrats to supply the 60 votes to defeat a filibuster, eliminating the need for a rules change. In exchange, they sought a commitment from Republicans to oppose changes in Senate rules on Supreme Court nominees when another opening came along, especially if the next vacancy would change the ideological balance of the court. “Given what had just happened with Merrick Garland, I thought it was completely reasonable to expect some sort of concrete guarantee,” said Coons, who as a member of the Judiciary Committee was central to the talks.

The talks bogged down over what form that Republican commitment would take and how it would be enforced, as well as unease among other Democrats about angering base voters who were furiously demanding unyielding resistance to Trump.

Some Republicans said privately that they could not fathom that Democrats would filibuster Gorsuch, given that his presence on the court would not be seen as a major shift. Still, the negotiations were alarming both Republican leaders and conservative activists enough that they began reaching out to lawmakers to urge them not to take part. They became worried that McConnell might not be able to nail down the votes to overcome a filibuster if Democrats proceeded. Just as much of a concern was the possibility that the filibuster might be preserved for the next court fight, likely to be one with greater consequences. But Republicans also took comfort in their expectation that Senate Democrats were under such intense pressure from their constituencies that an agreement would remain elusive.

“I don’t think the Democratic base would have allowed that at the time,” said Sen. John Cornyn of Texas, the No. 2 Senate Republican.

Ultimately, Democrats forced a procedural showdown on the Republican move to bring the Gorsuch nomination to the floor in early April. Democrats briefly halted the nomination when Republicans fell short of the preliminary 60-vote threshold on a vote of 55-45, with four Democrats joining them.

McConnell then set up a procedural vote that essentially lowered the threshold for advancing the nomination to a simple majority. It passed on a straight party-line vote of 52-48. Gorsuch was then confirmed 54-45, with three Democrats on board. (Coons and Bennet both opposed his confirmation, though Bennet had voted to break the filibuster.)

The ability to filibuster a Supreme Court nominee was officially dead. Schumer said he had no regrets about the tactic, and that Gorsuch’s performance on the bench since being confirmed only made him more certain.

“Justice Gorsuch was an extreme nominee, and his recent record vindicates our decision to do everything we could to stop him,” Schumer said.

Democrats also say that McConnell would have tried to simply change the rules on the next nominee even if they had held back on Gorsuch. That is most likely true. But if a bipartisan agreement were in place, he might be short of the votes to do so. McConnell now has an even narrower majority, and, with the continued absence of McCain, only one Republican would have to resist to prevent McConnell from succeeding.

“We would absolutely be better off now if we were in a place where the rules prevented the confirmation of a new justice with a less than 60-vote margin,” Coons said. “Looking back on it, we would be in a much better position.”

But there is no undoing it. And Democrats must now struggle mightily if they are to prevent the second Supreme Court confirmation of the Trump era without the power they lost last year.