There is no bipartisan compromise in sight as the Senate heads for a showdown over the Supreme Court that is likely to alter longstanding chamber norms and rules, thanks to a tense partisan environment and distrust resulting from past judicial battles.

Senate Democrats solidified enough votes Monday to filibuster Judge Neil Gorsuch, President Donald Trump’s nominee to the Supreme Court. Senate Republicans will likely deploy the so-called nuclear option to change Senate rules by a majority vote, and lower the threshold to end debate on Supreme Court nominees from 60 to a majority, so Gorsuch can overcome the filibuster.

[It’s Official: Filibuster of Gorsuch Starts Nuclear Option Countdown]

Sen. Chris Coons announced his opposition Gorsuch on Monday during the Judiciary Committee meeting to consider the nomination, thus pushing Democrats over the filibuster threshold. But the Delaware lawmaker added a caveat.

“I am not ready to end debate on this issue,” he said. “So I will be voting against cloture unless we are able, as a body, to finally sit down and find a way to avoid ‘the nuclear option’ and ensure that the process to fill the next vacancy on the court is not a narrowly partisan process.”

Such a bipartisan compromise, however, does not appear likely. Politics and hard feelings over past court battles have driven members of both parties to their respective corners, and no one is backing down. The Judiciary Committee voted 11-9 to advance the Gorsuch nomination to the floor, where debate will begin on Tuesday and likely conclude on Friday.

[Here’s How the Senate Gorsuch Debate Will Likely Play Out]

Sen. John McCain said there was no bipartisan group resembling the “gang of 14,” which averted a similarly looming Senate rules change over judicial nominees in 2005. The Arizona Republican said there were some informal efforts to compromise, but he was not optimistic they would be successful.

“Any effort being made to avoid it, I’m very supportive of,” McCain said last week. “I’m not sure we’re going to be able to.”

Sen. Bob Corker bemoaned the lack of senators on both sides of the aisle who are willing to take tough votes in the face of political pressure not to compromise.

“The base of each of our parties now drives us to extremes,” the Tennessee Republican said. “And neither party is willing to stand up to their base. That’s the problem. That’s why the Senate is where it is today.”

Outside pressure

Senators up for re-election in 2018 have been facing intense pressure from the left and the right over the Supreme Court.

More Democrats have been in the spotlight since the Senate Democratic caucus is defending 25 Senate seats as opposed to Republican’s nine. Ten of those Democrats are running in states that Trump won last fall.

And, some lawmakers said, outside political pressure from their party bases has dampened prospects for compromise.

“Listen, the pressure on these folks is real,” Sen. Lindsey Graham said of Senate Democrats. The South Carolina Republican noted that he has drawn primary opponents in the past over his support for former President Barack Obama’s Supreme Court nominees.

“There are very partisan people on both sides of the aisle that look at judges as the ultimate prize and they don’t want you to vote for anybody that doesn’t share their world view,” Graham said.

Outside groups on both sides of the Gorsuch debate have been active, mobilizing their members and pushing senators to stand their ground for or against the nominee.

The conservative Judicial Crisis Network has led a coalition of more than 50 like-minded groups pledging to spend $10 million on the campaign supporting Gorsuch’s nomination.

On the Democratic side, roughly two dozen groups have launched a “People’s Defense” campaign, though it is not clear how much money has been spent on their campaign against Gorsuch.

Marge Baker, executive vice president of People for the American Way, which is part of the People’s Defense coalition, declined to comment on how much money her group had spent.

“I can tell you it’s not $10 million,” she said.

Baker, who has been at People for the American Way for 14 years, said her group has developed research reports on Gorsuch’s record, held events in the states, mobilized its members to phone and write to senators, and she has seen a new wave of energy.

“I’ve been doing this for a very long time,” she said. “This is the most I have seen the base activated on any judicial nomination.”

Baker said recent Supreme Court decisions around campaign finance and voting rights have mobilized the more liberal Democratic base.

“I think what’s happening, at least on the Democratic side of the aisle, the senators are understanding how important this issue is to their base, in a way that I think, frankly, has perhaps not been there before,” she said.

And those who buck their party and support Gorsuch could face consequences.

Leaders from liberal groups attempted to deliver a petition, signed by 230,000 people, to the Democratic Senatorial Campaign Committee on Monday. They were urging the DSCC not to spend campaign funds for the three Democrats up for re-election who are voting for Gorsuch, as well as any Democrat who strikes a deal to advance Gorsuch’s nomination.

“The base’s disappointment will be evident,“ Baker said.

The intraparty pressure on Republicans to stand their ground has been less intense, given the confidence that most Republicans would back Gorsuch. Conservatives were not worried that even the more vulnerable Sen. Dean Heller, who is running for re-election in Nevada, would buck the party.

“Judge Gorsuch is so well-qualified,” said Carrie Severino of the Judicial Crisis Network. “I think it would have been really surprising to see any of those Republicans vote against him.”

Hard feelings

Bitter past battles over judicial nominees have also strained any attempt at a bipartisan solution to avert the nuclear option.

Democrats point to the Republicans’ refusal to consider Obama’s nominee, Judge Merrick Garland, for the seat left open by the death of Judge Antonin Scalia in February 2016. That led to a record-setting vacancy on the court. Republicans say Democrats are to blame for the rule breakdown after changing the debate threshold on lower court and executive branch nominees in 2013.

“It is such a gut-wrenching issue on both sides, I think it becomes increasingly difficult to figure out whom we trust to negotiate anything,” Senate Minority Whip Richard J. Durbin said.

Even Coons, who pegged his cloture vote on the prospect for a Senate rules compromise, did not sound hopeful they would reach a solution.

“I’m very skeptical … given just how much distrust and disagreement there is, how much what’s happened to Judge Garland and now happening to Judge Gorsuch has divided our parties,” Coons told CNN on Monday. “[I’m] quite skeptical we can come to any sort of understanding.”