Senate Democrats are reportedly gearing up for a potential fight over Donald Trump’s U.S. Supreme Court pick, with some liberal activists urging them to do everything possible to block any nominee from the Republican president-elect, according to a Reuters report.

The Republican-led Senate last year refused to consider outgoing President Barack Obama’s nomination of appeals court judge Merrick Garland for a lifetime post on the court, which prompted some Democrats to accuse Republicans of stealing a Supreme Court seat.

Scalia’s replacement could tilt the ideological leaning of the court for years to come, restoring the long-standing conservative majority that disappeared with Scalia’s death. Trump’s nominee could influence the court on a wide range of issues including abortion, the death penalty, religious rights, presidential powers, gay and transgender rights, federal regulations and others.

Liberal groups are gearing up for a battle, with the People For the American Way calling the judges on Trump’s list of candidates “very extreme.” Senate Democratic leader Chuck Schumer has said it is hard for him to imagine Trump picking a nominee who Democrats could support, and said he would “absolutely” fight to keep the seat vacant rather than let the Senate confirm a Trump nominee deemed to be outside the mainstream.

Senate Democrats may be in a position to hold up Trump’s selection indefinitely. Senate rules require 60 votes in the 100-seat chamber to overcome a procedural hurdle called a filibuster on Supreme Court nominees. There are 52 Republican senators. Assuming all 52 back Trump’s nominee, Senate Majority Leader Mitch McConnell either would need to lure eight Democrats to his side or change the rules and ban the filibuster for Supreme Court nominations.  Many of those Democratic seats are in Republican-leaning states Trump won in the November 8 election, including West Virginia, Missouri, North Dakota, Indiana, Montana, Michigan and Ohio.

Republicans likely will target these and other Democrats in hopes of coaxing them into backing Trump’s nominee. That means Democratic senators such as West Virginia’s Joe Manchin, Indiana’s Joe Donnelly and Missouri’s Claire McCaskill could face extra pressure not to block Trump’s Supreme Court nominee.