(CNN) -- Four Senate Democrats announced Monday they plan to oppose Neil Gorsuch, bringing the Democratic caucus to the 41 votes needed to sustain a filibuster against the Supreme Court nominee.
The announcement sets Republicans up to change Senate rules -- referred to as the "nuclear option" -- to lowering the threshold of advancing Supreme Court nominees to just 51 votes from 60.
The Senate Judiciary Committee voted 11-9 along party lines to advance Gorsuch's nomination to the full Senate.
With Sens. Chris Coons of Delaware, Dianne Feinstein of California, Mark Warner of Virginia and Patrick Leahy of Vermont all saying Monday they could not support Gorsuch, Democrats reached the 41 votes they needed to prevent the advancement of Gorsuch's nomination under current chamber rules.
"I am not ready to end debate on this issue, 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 the process to fill the next vacancy on the court is not a narrowly partisan process, but rather an opportunity of both parties to weigh in and ensure we place a judge on the court who can secure support from members of both parties," Coons said at the Senate judiciary committee hearing on Gorsuch's nomination, becoming the 41st senator to say he will take part in the filibuster.
Coons told CNN's Wolf Blitzer immediately after his announcement that he understood the consequences of his decision, but also repeated his pledge that he's open to negotiating with Republicans to find an agreement on avoiding the nuclear option.
"I said, 'I will vote against closure unless the Republicans and Democrats in the Senate can somehow find an agreement that is trustworthy and reliable, where on the next Supreme Court nominee, they won't change the rules and we will have input and a more confirmable, consensus nominee will be put in front of the Senate,'" Coons said. "I'm not saying that I'm insisting that we force the Republican majority to break the rules. That's a choice they're going to have to make."
The White House is "disappointed" that Democrats will have enough votes to sustain a filibuster against President Donald Trump's Supreme Court nominee Neil Gorsuch, press secretary Sean Spicer told reporters following the filibuster news.
"If the Democrats get their way, and the numbers are looking that way, this is going to be the first successful filibuster of a nominee to join the Supreme Court, which is clearly unprecedented," Spicer said, adding, "With a vote on Judge Gorsuch on Friday, the American people see which senators are willing to keep this seat open to get in the way of President Trump making progress on one of his most significant choices so far."
Knowing full well that the filibuster would likely lead to Republicans using the "nuclear option," Leahy shared his struggle over his decision but ultimately said he "cannot vote solely to protect an institution," adding that he considers Americans' rights at risk with Gorsuch's nomination.
"I've often said the Senate at its best can and should be the conscience of the nation, but I must first and foremost vote my conscience," Leahy said. "I will not and can not support advancing this nomination."
Republicans, who hold a 52-48 majority, needed a total of 60 votes to end the filibuster. As of Monday morning, they had 55 votes, including three Democrats who are voting with them.
Three senators -- two Democrats and one independent -- remain undecided. However, even if those three senators were to side with Republicans, it wouldn't be enough to avoid the filibuster.
The majority party can still get around the filibuster by changing Senate rules and using the controversial "nuclear option" to lower the threshold needed to end debate.
Sen. Michael Bennet, a Democrat from Gorsuch's home state of Colorado, said Monday he hasn't decided how he will vote on confirmation, but plans to oppose the filibuster from fellow Democrats. "I will oppose efforts to filibuster the nomination, and strongly encourage my colleagues not to use the nuclear option," he said in a statement.
Judiciary Committee vote
Before voting, senators engaged in an at-times testy debate over not only Gorsuch, but Republican action to block President Barack Obama's Supreme Court nominee, Merrick Garland, last year.
"This action by my colleagues was unacceptable and has scarred this process and this body," Coons said. "There has never been a partisan filibuster of a Supreme Court nominee in history; and while technically correct, I question what a seven month refusal to hold a hearing or vote is -- if not the longest, partisan filibuster on this committee ever."
Republicans argued that Democrats would essentially oppose any Trump nominee.
"If (Democrats) are going to oppose Neil Gorsuch to the Supreme Court of the United States, they will never vote and never support a nominee of this President. Because in the end, I think that's really what gets their goat the most," said Sen. John Cornyn of Texas. "We keep hearing about Merrick Garland, but I guarantee if Hillary Clinton had the presidency, we'd never hear Merrick Garland's name again because she would have had the opportunity to pick her own nominee to the Supreme Court."
Sen. Lindsey Graham, R-South Carolina, accused Democrats of obstructing Gorsuch's nomination and expressed remorse that Republicans will have to use the nuclear option to get him confirmed.
"We will not have a successful filibuster of a Supreme Court nominee because if we have to we will change the rules, and looks like we are going to have to," he said. "I hate that. I really, really do."
Spending from outside groups has also been a hotly contested debate in Gorsuch's nomination. Democrats have criticized Gorsuch for not speaking out against third party groups, with undisclosed donors, who have spent millions in support of his nomination.
The debate continued during the hearing Monday.
"This nomination is not the usual nomination. It comes in a different way and it has proceeded in a way of excessive spending of dark money that in the time I have been on this committee I have never seen before," said Feinstein, the top Democrat on the committee.
Committee Chairman Chuck Grassley, however, pointed to liberal groups that supported Supreme Court nominees appointed by Obama, like Garland.
"Now, I've never heard any Democrat complain about all that money that was spent last year," Grassley said.
Sen. Ben Cardin (Maryland) -- Like Feinstein, Cardin also hasn't announced whether he'll run for re-election. He told CNN last week that he plans to vote against Gorsuch's nomination in the end, but he hasn't made a decision on whether he'll vote to maintain the filibuster.
"I came out today against the nominee, so I'll be voting 'no' on the substance. I'm waiting to see what the Republican leadership (does), how they present the nomination on the floor and how they work with the Democrats. There's still a lot of anxiety out there because of the way they handled the Garland nomination. So I will wait to see how they handle this nomination before deciding what I will do on procedural votes." -- To CNN on 3/28/2017
Sen. Bob Menendez (New Jersey) -- Menendez also hasn't announced a 2018 run but he has reportedly started raising campaign funds. Like Feinstein and Cardin, he's considered safe if he decides to run. The New Jersey senator told reporters that he's still deciding on Gorsuch, but "when I come to a conclusion on how I'm voting on Gorsuch, I'll decide on how I'm voting in the whole process."
Independent Sen. Angus King (Maine) -- While King is an independent, he's considered part of the Democratic caucus. He's been fairly quiet about Gorsuch of late. His seat is also considered safe in 2018.
Democrats who will vote for Gorsuch and against filibuster
Sen. Joe Manchin (West Virginia)
Sen. Heidi Heitkamp (North Dakota)
Sen. Joe Donnelly (Indiana)
Democrats who will vote against filibuster
Sen. Michael Bennet (Colorado)
Democrats who plan to filibuster
1. Senate Minority Leader Chuck Schumer (New York)
2. Independent Sen. Bernie Sanders (Vermont)
3. Sen. Bob Casey (Pennsylvania)
4. Sen. Ron Wyden (Oregon)
5. Sen. Patty Murray (Washington)
6. Sen. Elizabeth Warren (Massachusetts)
7. Sen. Jeff Merkley (Oregon)
8. Sen. Tom Carper (Delaware)
9. Sen. Tammy Baldwin (Wisconsin)
10. Sen. Bill Nelson (Florida)
11. Sen. Cory Booker (New Jersey)
12. Sen. Mazie Hirono (Hawaii
13. Sen. Tom Udall (New Mexico
14. Sen. Jack Reed (Rhode Island)
15. Sen. Chris Murphy (Connecticut)
16. Sen. Sheldon Whitehouse (Rhode Island)
17. Sen. Tim Kaine (Virginia)
18. Sen. Kamala Harris (California)
19. Sen. Al Franken (Minnesota)
20. Sen. Debbie Stabenow (Michigan)
21. Sen. Ed Markey (Massachusetts)
22. Sen. Chris Van Hollen (Maryland)
23. Senate Minority Whip Dick Durbin (Illinois)
24. Sen. Jeanne Shaheen (New Hampshire)
25. Sen. Gary Peters (Michigan)
26. Sen. Maggie Hassan (New Hampshire)
27. Sen. Amy Klobuchar (Minnesota)
28. Sen. Martin Heinrich (New Mexico)
29. Sen. Tammy Duckworth (Illinois)
30. Sen. Kirsten Gillibrand (New York)
31. Sen. Richard Blumenthal (Connecticut)
32. Sen. Maria Cantwell (Washington)
33. Sen. Brian Schatz (Hawaii)
34. Sen. Catherine Cortez Masto (Nevada)
35. Sen. Claire McCaskill (Missouri)
36. Sen. Sherrod Brown (Ohio)
37. Sen. Jon Tester (Montana)
38. Sen. Dianne Feinstein (California)
39. Sen. Patrick Leahy (Vermont)
40. Sen. Mark Warner (Virginia)
41. Sen. Chris Coons (Delaware)
This story will be updated as CNN receives updated information.
CNN's Kevin Liptak contributed to this report.