WASHINGTON — Nearly 14 months since the death of Supreme Court Justice Antonin Scalia, the Senate finally began action Thursday to replace him with federal appeals court Judge Neil Gorsuch, marking the end of a divisive process that could forever change the way justices are confirmed and further weaken the Senate's bipartisan traditions.

Faced with a Democratic filibuster of the 49-year-old Coloradan, like Scalia a fierce conservative and strict interpreter of the Constitution, Senate Republicans set the stage for a controversial rules change that will allow them to confirm Gorsuch with a simple majority vote.

Democrats won the first, short-lived victory by denying President Trump's nominee 60 votes, since only four Democrats had aligned with the chamber's 52 Republicans to support his confirmation. The 55-45 vote to end debate on the nomination therefore was defeated.

But Senate Majority Leader Mitch McConnell, R-Ky., who voted against it to preserve his next move, was to invoke the "nuclear option," changing Senate rules to get around the filibuster. After 30 more hours of debate, a final vote on Gorsuch's confirmation likely will take place Friday evening.

"There's a reason why it's called the nuclear option," Senate Democratic leader Chuck Schumer, D-N.Y., said on the Senate floor before the series of votes began. "It's the most extreme measure, with the most extreme consequences."

"The consequences for the Senate and for the future of the Supreme Court will be far-reaching," Schumer said. The 60-vote threshold in the Senate has been "the guardrail of our democracy ... when it comes to the courts, the guardrails are being dismantled."

McConnell urged Democrats Thursday morning to have a last-minute change of heart and let Gorsuch's nomination go through. Otherwise, he warned sternly, "This will be the first and last partisan filibuster of a Supreme Court nomination."

He emphasized that a successful partisan filibuster would be the first ever mounted against a Supreme Court nominee in the Senate's 230-year history. “This is the latest escalation in the never-ending judicial war,” McConnell said.

Schumer said Democrats "have principled reasons to vote against this nominee." Among them, he said, are Gorsuch's votes for corporate interests over average Americans, his ties to President Trump and his "deeply-held, far-right, special-interest judicial philosophy that is far outside the mainstream."

But Senate Judiciary Committee Chairman Chuck Grassley, R-Iowa, said Democrats recognize that Gorsuch -- a graduate of Columbia, Harvard and Oxford who clerked for two Supreme Court justices and has served a decade as an appeals court judge -- deserves to be confirmed.

"That’s why this is an especially sad state of affairs," Grassley said. "At the end of the day, we’re left with an exceptional nominee, with impeccable credentials, and broad bipartisan support."

The number-two ranking Democrat, Sen. Richard Durbin, D-Ill., ridiculed Republicans for suggesting Democrats brought the Senate to this final action. He said the GOP leader cannot utter the name of Merrick Garland, who Republicans blocked from the court all last year.

“For the first time in the history of the Senate, for the first time ever, this Republican-led Senate refused to give this nominee a hearing and a vote,” Durbin said. Rather than voting on Gorsuch, he said, “We should be celebrating the one-year anniversary of Merrick Garland on the Supreme Court.”

Democrats remain angry that Republicans refused to consider former president Barack Obama's nomination of Garland to replace Scalia, who died on Feb. 13, 2016. Garland was considered a moderate choice by the liberal president, but leaders of the Republican-held Senate said Obama should not be allowed to put someone on the court during his last year in office. Instead, GOP leaders said Obama's successor should choose the nominee.

Republicans noted that Democrats first invoked the "nuclear option." In late 2013, former Senate majority leader Harry Reid, D-Nev., convinced Senate Democrats to change Senate rules to prevent Republicans from blocking Obama's lower court and Cabinet nominees.

Gorsuch, the man caught in the middle of the bitter partisan fight, is expected to become the nation's 113th Supreme Court justice soon after the procedural maneuvering ends on Friday. He would be sworn in shortly thereafter and would be on the bench for the last two weeks of oral arguments of the court's 2016 term later this month.

The cerebral judge has expressed great admiration for Scalia, and shares the late justice's conservative views on how to interpret the Constitution. He has served as a judge on the Denver-based U.S. Court of Appeals for the 10th Circuit for the past decade.