Washington — The Senate Republicans who kept a Supreme Court seat vacant for more than nine months last year appear poised to change one of the Senate’s most-treasured rules in order to confirm Judge Neil Gorsuch to the position by a simple majority vote.

Amid mutual blame-casting so bitter that it’s bound to poison future deliberations, no Republican on Tuesday publicly veered away from the potential rules change ominously known on Capitol Hill as the “nuclear option.”

Absent some unexpected plot twist, the Senate is on course to confirm Gorsuch, end filibusters on Supreme Court nominees and leave recriminations even among the victors by the end of the week.

“It should be unsettling to everyone that our colleagues across the aisle have brought the Senate to this new low,” Senate Majority Leader Mitch McConnell, R-Ky., said on the Senate floor Tuesday morning, adding that “history will be watching, and the future of the Senate will hang on their choice.”

Republicans control 52 Senate seats. Sixty are currently needed to limit debate, but Gorsuch supporters can count no more than 56, making it likely McConnell will trigger the “nuclear option.” That would mean 51 votes would limit debate, easing Gorsuch’s path.

In a sign that backstage maneuvering and vote-whipping continue, the chair of the Senate Republican Conference, Sen. John Thune, of South Dakota, declined repeated requests Tuesday to say whether Republican leaders had lined up the votes necessary to support the controversial rules change. Instead, Thune repeatedly stated that “we have the votes to confirm the judge.”

The Senate Judiciary Committee approved Gorsuch’s nomination on Monday by an 11-9 vote that broke along party lines.

Though three Democrats from the red states of West Virginia, North Dakota and Indiana have announced they will vote for Gorsuch, more than 40 have declared their opposition. Sen. Michael Bennet, D-Colo., said he would not back a filibuster but was undecided on Gorsuch. Democrats have enough support to sustain the endless debate of a filibuster, which can be cut off only with the approval of 60 senators.

Most Democrats are holding firm, in large part because of Republicans’ refusal last year to consider then-President Barack Obama’s nominee, Judge Merrick Garland of the U.S. Court of Appeals for the District of Columbia Circuit. Obama nominated Garland on March 16, 2016, following the Feb. 13 death of Antonin Scalia.

“What the majority leader did to Merrick Garland, by denying him even a hearing and a vote, is even worse than a filibuster,” Senate Minority Leader Chuck Schumer, D-N.Y., said on Tuesday.

Republicans, in turn, characterize the Democratic effort to block a vote on Gorsuch’s nomination as the first-ever “partisan” filibuster of a Supreme Court nominee. On Oct. 1, 1968, 19 Democrats and 24 Republicans joined to sustain a filibuster that prevented Justice Abe Fortas from serving as chief justice. Fortas was dogged by ethics issues.