WASHINGTON — Senate Republicans are expected to confirm Donald Trump’s Supreme Court appointee Neil Gorsuch on Friday after clearing the way Thursday by triggering the “nuclear option” to effectively end filibusters of high-court nominees.

Senate Majority Leader Mitch McConnell (R-Ky.) took the controversial step Thursday of reinterpreting Senate rules to lower the number of votes needed to break filibusters from 60 to 51 after Democrats blocked an up-or-down confirmation vote for Gorsuch.

McConnell’s action came on a day of impassioned speeches and angry finger-pointing about the Senate’s escalating political fights over judicial appointments, and led lawmakers and experts to predict increasing partisanship in the Senate and on the Supreme Court.

“This will be the first and last partisan filibuster of a Supreme Court nomination,” McConnell said before he pulled the trigger and as he blamed Democrats for forcing him to scrap a centuries-old rule of the Senate.

Senate Minority Leader Chuck Schumer (D-N.Y.) put the blame on McConnell. “It doesn’t have to be this way,” Schumer said. “When a nominee doesn’t get enough votes for confirmation, the answer is not to change the rules. It’s to change the nominee.”

The confirmation vote planned for Friday will end the 14-month vacancy on the Supreme Court, leaving only eight of the nine seats filled, since the death of Justice Antonin Scalia. Gorsuch’s approval will restore the conservative bloc’s five-vote majority.

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McConnell’s rule change for Supreme Court nominations completes a process begun in 2013 when Democrats, then in the majority, triggered the nuclear option for a president’s lower court and executive appointments.

That means the Senate minority can no longer filibuster any presidential nominees requiring Senate confirmation. Senators can use procedure only to block legislation.

Most Democrats and many Republicans said they rued the rules change.

“I fear today’s action will irreparably damage the uniqueness of the Senate, and along with it, any hope of restoring meaningful bipartisanship,” said Sen. John McCain (R-Ariz.), who helped head off use of the nuclear option on judicial nominations a decade ago.

Jeffrey Segal, an expert on judiciary at Stony Brook University, said Trump and future presidents with a Senate majority will no longer have to reach out to the minority party in selecting high court justices. “This will lead to more extreme nominees,” he said.

McConnell and Schumer traded blame as Thursday’s session began.

“The opposition to this particular nominee is more about the man who nominated him and the party he represents than the nominee himself,” McConnell said.

But Schumer pointed out that McConnell did not give a hearing or a vote to President Barack Obama’s nominee, U.S. Circuit Court Judge Merrick Garland, after Scalia’s death in February 2016.

The rules change process followed a script.

An hour after the day’s session began, Democrats filibustered Gorsuch. The 52 Republicans and three Democrats facing election in states Trump won last year fell short of the 60 votes needed to proceed.

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McConnell then initiated the series of parliamentary motions need to change the rules, prevailing in each step along party line votes.

Schumer responded with points of inquiry to reinforce his arguments and called for votes on a motion to postpone the final vote until the Senate will return from its two-week recess and to adjourn until 5 p.m. Thursday. Both motions lost on party-line votes.

Senate Republicans and their three Democratic allies then ended the Schumer-led filibuster with a 55-45 vote.