The change would be historic and would long out live the current controversy concerning Judge Neil Gorsuch --President Donald Trump's nominee to the Supreme Court. It would further transform the one chamber of Congress where minorities can block the agendas of the majority.
Gorsuch needs 60 votes to move forward with Senate procedure before there's an up-or-down vote.
After Gorsuch completed his testimony, Senate Minority Leader Chuck Schumer took to the floor to announce his "no" vote and encourage his colleagues to follow suit. Schumer did so, knowing that such a filibuster could trigger Republicans to launch the so called "nuclear option," changing Senate rules to lower the voting threshold to a simple majority and do away with the filibuster for Supreme Court nominees.
For his part, Senate Majority Leader Mitch McConnell, supported by Vice President Mike Pence, suggested that one way or another, Gorsuch would make the court, even if Republicans were forced to change the rules. He announced Tuesday that the final vote would be Friday, April 7.
While Democrats are avoiding the combative word "filibuster" — and Republicans so far are mostly dodging the word "nuclear," both sides are engaged in a furious head count.
Democratic leaders want to make sure the opposition is in place, and Republicans are taking the pulse of traditionalists who might chafe at a rules change.
How did we get here?
Hands on both sides of the aisle are dirty.
"We shouldn't be surprised to see tensions boil over on the question of whether or not to confirm the president's Supreme Court nominee," said Sarah Binder, an expert on the filibuster and a professor of Political Science at the George Washington University. "We've seen a decade — if not decades — of a partisan parliamentary arms race over what goes on in the Senate."
The use of the filibuster — from a dutch word meaning "pirate" — is not new. According to the Senate Republican Communications Center, it became popular in the 1850s.
It faded away in the House, but the smaller Senate continued with the practice to ensure a level of protection for the minority.
By 1917, senators adopted a rule that allowed the Senate to end a debate by so called "cloture." In 1975, the Senate reduced the number of votes required for cloture from two-thirds to three-fifths — which is now 60 votes.
Binder told CNN that as far as Supreme Court nominees go the only successful filibuster was to elevate Justice Abe Fortas to Supreme Court Chief Justice. But that was complicated by allegations of ethics violations.
Reid's move in 2013
Indeed, it was only in 2013 when then-Senate Majority Leader Harry Reid changed the rules for lower court judges and executive branch agencies, eliminating the ability to filibuster those nominations. But he didn't extend that change to Supreme Court picks.
At the time, Republicans lambasted the move, particularly the traditionalists.
"We are approaching a slippery slope that will destroy the very unique aspect of this institution called the US Senate," said Sen. John McCain, an Arizona Republican.
Republicans have been quick to remind the public that the seed for a rules change came from Democrats four years ago.
"This is the step they took in 2013," Sen. Mike Lee, R-Utah, told CNN on Tuesday. "We are going to get Judge Gorsuch confirmed — this is a good judge — this is a judge who interprets the law based on what it says rather than what he might wish it might say, and we intend to get him confirmed," he said.
Democrats still angry over Merrick Garland
Democrats, not surprisingly, see things differently.
They say it is the Republicans who have changed the landscape for the Supreme Court when they failed to hold hearings for President Barack Obama's nominee Merrick Garland, following the death of Antonin Scalaia in February 2016.
Obama — once a constitutional scholar -- spoke about his candidate at the University of Chicago in April 2016.
"Merrick Garland is an extraordinary jurist who is indisputably qualified to serve on the highest court of the land. And nobody really argues otherwise," Obama said. "No one has plausibly made an argument that this is not the kind of person we'd want on the Supreme Court. The question then becomes: Why is it so hard for the guy just to get a hearing and a vote?"
All in all, Garland's nomination languished for 300 days, as Republicans led by McConnell refused to hold hearings and said they wanted the next president to decide who would fill the vacant seat on the High Court.
When Trump unexpectedly won in November, the Republican's strategy paid off.
Now, both sides find themselves at a new precipice. Changing the rules in a traditionalist place like the Senate, although not a done deal, raises questions.
Will Senate traditionalists buy into it?
Sen. Susan Collins told CNN's Ted Barrett that she hoped the Democrats will withdraw the filibuster threat.
"I really hope it doesn't come to that," the Maine Republican said, adding later, "I don't want to change the rules of the Senate and I hope we're not confronted with that choice."
Cass Sunstein, a former official in the Obama administration and a constitutional scholar suggested in a recent piece for Bloomberg View that a filibuster would not be the best move.
He suggested that Democrats might either vote to confirm Gorsuch on the grounds that he is a "distinguished nominee" or they might vote a "firm but nonetheless gracious and respectful 'no' without resorting to the filibuster."
"It reflects a sensible understanding of the system of separation of powers, and it would be a form of statesmanship," he wrote.
Christopher Kang, the National Director of the National Council of Asian Pacific Americans who opposes Gorsuch sees things differently.
He said that no Democrat looks forward to a filibuster but he believes that Gorsuch is not within the mainstream.
"If President Trump had nominated someone more in the mainstream, a filibuster wouldn't be part of the conversation," Kang said.
"Republican complaints about a 60-vote threshold are beyond hypocritical," Kang said. "In addition to their unprecedented mistreatment of Judge Garland's nomination, they filibustered President Obama's first judicial nominee— even though he had bipartisan support from then Sen. (Richard) Lugar (R-Indiana)."
Kang was referencing Obama's first judicial nominee, David Hamilton, who faced a filibuster in 2009
and who was up for an open seat on the 7th US Circuit Court of Appeals.
The possibility of a rules change also raises the question of what will happen down the line when the President is of one party and the Senate another. Could that prompt more Garland-like scenarios and lead to extended periods of a short staffed court? The prospect also begs the question if whether it would open the door of less mainstream candidates on both sides.