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. Republicans need eight Democrats to end the filibuster. McConnell mostly likely will draw from a 2013 Democratic parliamentary playbook, when then-Majority Leader Harry Reid invoked the nuclear option for executive branch and lower-court nominees.

McCain said last week that he was talking with senators in both parties to try to avoid using the "nuclear option" to change the rules.

The political wrangling over President Donald Trump's choice to fill the vacant US Supreme Court seat has set up what could turn out to be a major battle in the Senate.

Top Democrat Chuck Schumer pointed to McConnell's refusal to hold hearings or a vote on then-president Barack Obama's Supreme Court nominee Merrick Garland, who had been tapped to replace Scalia.

Sen. Michael F. Bennet (D-Colo.) said on Monday that he would join Republicans in trying to end the filibuster, but did not say whether or not he would vote for Gorsuch. "That could not be further from the truth", said Schumer (D-N.Y.).

If the nuclear option is necessary to confirm Judge Gorsuch, Republican senators should use it.

"Striking down the sixty vote threshold would be extremely destructive to the United States Senate but even more so a tragedy to the country", said Blumenthal.

Democrats made clear they had no plans to do so, and blamed Republicans for pushing them to attempt a almost unheard of filibuster of a well-qualified Supreme Court pick. And based on their performance with the Gorsuch nomination, they won't have a leg to stand on.

Collins said Gorsuch deserves to be on the high court and that she's "committed" to making sure he gets confirmed. "McConnell broke 230 years of Senate precedent, didn't even allow Judge Garland a hearing or a vote", Schumer said.

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"But this has very severe long-term consequences for this body, because we've just abandoned one of the pillars of it", McConnell told reporters of the tactic at the Capitol.

Instead, the parties spent much of Tuesday trading blame.

But it was Senate Republicans who past year refused to even consider former president Barack Obama's nomination of appellate judge Merrick Garland to fill the same high court vacancy that Mr Trump has selected Mr Gorsuch to fill.

Sen. Susan Collins, R-Maine, who had hoped that there could be a deal worked out with Democrats to avert the showdown, said Tuesday that she has no such expectations.

There are four Democrats who have said they will buck their party and vote for cloture: Joe Manchin of West Virginia, Heidi Heitkamp of North Dakota, Joe Donnelly of IN and Michael Bennet of Colorado.

"Later today, colleagues will continue to debate the nomination of Judge Gorsuch".

"Judge Gorsuch is independent, he's fair, he's got one of the most impressive resumes we've ever seen, and he's earned the highest possible rating from the group the Democratic Leader calls the "gold standard" for evaluating judicial nominations".

"First of all, I think it's important to recognize that there is absolutely no basis for filibustering such an eminently qualified nominee", Collins said. Once he becomes a justice, we will likely be only one vote shy of reversing this awful decision.

Scalia's seat has remained open for 14 months, allowing Trump to nominate Gorsuch, a conservative in the mold of Scalia who has served for more than a decade on the 10th U.S. Circuit Court of Appeals in Denver.