By Lawrence Hurley and Richard Cowan
WASHINGTON (Reuters) - The U.S. Senate is set for a vote on Thursday that will test the resolve of Democratic opposition to President Donald Trump's Supreme Court nominee, Neil Gorsuch, and likely prompt Republicans to change the chamber's rules to allow his confirmation by the end of the week.
The Senate vote, expected at 11 a.m. (1500 GMT), is a bid by Republican leaders to try to end a Democratic procedural effort called a filibuster aimed at blocking Gorsuch's confirmation to a lifetime post on the court.
Republicans were expected to fall short of being able to halt the filibuster, but have said they have the votes needed to change long-standing Senate rules to prohibit such a procedure against Supreme Court nominees. Republicans said Gorsuch would be confirmed on Friday one way or the other.
Senate confirmation of Gorsuch, 49, would reinstate the nine-member court's conservative majority, allowing Trump to leave an indelible mark on America's highest judicial body and fulfill a top campaign promise by the Republican president.
"There is still time for them to support a nominee who even longtime Democrats have praised, or at the very least, do not block him with the first successful partisan filibuster in American history," Republican Senate Majority Leader Mitch McConnell said of the Democrats on Wednesday.
During Senate debate on Wednesday, various Republicans called the conservative Colorado-based federal appeals court judge "incredibly qualified," an "intellectual heavyweight" and "always true to the law."
Democratic Senate leader Chuck Schumer indicated, however, that Democrats intended to follow through on their filibuster pledge, having gathered more than the 41 votes they need to mount the effort. A filibuster requires a super-majority of 60 votes in the 100-seat Senate to proceed to a simple majority vote on a Supreme Court nominee or legislation. Republicans control the Senate 52-48.
"We Democrats believe the answer isn’t to change the rules, it’s to change the nominee, as presidents of both parties have done when a nominee fails to earn confirmation," Schumer said on the Senate floor.
Democrats accuse Gorsuch of being so conservative as to be outside the judicial mainstream, favoring corporate interests over ordinary Americans in legal opinions, and displaying insufficient independence from Trump.
They are also angry that Senate Republicans last year refused to consider former Democratic President Barack Obama's nomination of appellate judge Merrick Garland to replace conservative Justice Antonin Scalia, who died in February 2016, the same seat Gorsuch has been named to fill.
The rule change, which requires a simple majority, has been dubbed the "nuclear option," and Trump has encouraged McConnell to "go nuclear."
Ending the filibuster would make it easier for future Supreme Court nominees to be confirmed when the president and Senate leadership belong to the same party.
Republican Senator John McCain, known as a defender of Senate traditions, offered reluctant support for the rule change, but said it would likely lead to judicial nominees "from the extremes of both left and right."
The 60-vote threshold that gives the minority party power to hold up the majority party has forced the Senate over the decades to try to achieve bipartisanship in legislation and presidential appointments.
(Additional reporting by Andrew Chung and Richard Cowan; Editing by Peter Cooney.)