WASHINGTON — The top Democrat in the Senate is warning President-elect Donald Trump about his eventual Supreme Court choice: Name a “mainstream” nominee or Democrats will oppose the individual “with everything we have.”

“My worry is, with the hard right running the show, that the likelihood of the nominee being mainstream is decreasing every day,” New York Sen. Chuck Schumer said Wednesday in an interview.

Schumer made the comments a day after saying on MSNBC’s “The Rachel Maddow Show” that Democrats will “absolutely” do their best to keep the Supreme Court seat open if Trump doesn’t nominate someone whom Democrats could support.

The seat has been vacant for 11 months since the death of Justice Antonin Scalia last February. Senate Majority Leader Mitch McConnell, R-Ky., blocked consideration of President Barack Obama’s nominee, Judge Merrick Garland, saying the next president should make the pick. The strategy paid off, and the Republican Senate will consider whomever Trump nominates.

As minority leader, Schumer won’t have the same power as McConnell to block a nominee. But his words signal that Democrats could filibuster and force Republicans to round up 60 votes to move ahead. That will be a challenge for the GOP since they only hold 52 seats.

If Republicans can’t get enough Democratic votes, then they do have another option — change the rules and curb the filibuster for Supreme Court nominees. Former Senate Majority Leader Harry Reid, D-Nev., did that for lower court nominees and other nominations in 2013.

Schumer didn’t define what he meant by “mainstream.” But he did say on Maddow’s show that Garland, Obama’s unsuccessful pick, was “a very moderate, mainstream nominee.” Garland has been considered a liberal-leaning moderate in his years on the U.S. Court of Appeals for the District of Columbia Circuit.