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Senate Republicans are gearing up for the next step in the confirmation battle over Supreme Court nominee Neil Gorsuch and appear committed to invoking the so-called “nuclear option” of changing Senate rules while placing the blame at the feet of Democrats.

“It’s not too late for our Democratic colleagues to make the right choice,” said Senate Majority Leader Mitch McConnell in a statement Monday afternoon after Democrats had publicly marshaled enough votes to block Gorsuch from being confirmed under the body's current rules.

The Senate is slated to take an initial vote on President Donald Trump's choice to replace the late Justice Antonin Scalia this week. But 42 Democrats have publicly announced their opposition to the nomination and support for a filibuster.

Related: Democrats Hit Gorsuch Filibuster Threshold

In response, McConnell has left open the option of going nuclear, changing the Senate rules so that Supreme Court nominees can pass the Senate with a simple majority, instead of a 60-vote threshold. And most Republicans, even the most reluctant, appear ready to follow McConnell's lead.

Sen. Susan Collins, R-Maine, is troubled by the notion that the Senate might move down this path.

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“First of all I think it’s important to recognize that there is absolutely no basis for filibustering such an eminently qualified nominee. And I am very troubled by the fact that the Democrats have put us in this situation,” Collins said.

But the GOP moderate said she might support a rule change.

“If it’s necessary in order to get him confirmed I may have to vote that way, but I certainly don’t want to,” Collins said.

Any rules change needs the support of a simple majority of members. There are 52 Republicans so they can’t afford to lose more than two (given a potential tie-breaking vote by Vice President Mike Pence).

Related: What the Nuclear Option Is and Why It Matters

Sen. John McCain, R-Ariz., had been trying discuss ways to avert the extreme move with fellow concerned colleagues. Monday he said those talks are no longer happening.

“It’s over, it’s over, there was plenty of talk — conversations that I had — they didn’t come to fruition and they have enough declared (to support a filibuster) now that it’s over,” he said.

McCain and Collins mourn the changes that a rule change will cause. The filibuster — the 60 vote requirement — was put in place to force consensus.

McCain said that after a rule change the court will be more ideologically driven "on both sides depending on who’s in the majority."

“It’s bad for the Senate as an institution and I think it is bad for the court as well,” Collins said.

The newest Republican member, Sen. Luther Strange, R-Alabama, who replaced now-Attorney General Jeff Sessions, said that the battle that’s about to take place seems juvenile.

“It has all the appearances of a junior high school food fight but it’s a serious matter,” Strange said. “Very sad to see that we’re in this place but I think there’s no choice given the fact that Neil Gorsuch is a perfectly mainstream candidate. We’re in territory that we’ve never been in. … If we do, it will be the Democrats’ decision.”