Even before President Donald Trump announces his Supreme Court pick Tuesday night, one Democratic senator threatened to hold up the choice, potentially sparking a second straight year of partisan clashing over the vacancy.

Sen. Jeff Merkley, D-Ore., told Politico on Monday that he will filibuster Trump's choice. He called it a "stolen seat" because the Republican-controlled Senate did not vote on Merrick Garland, whom former President Barack Obama nominated last year for the late Justice Antonin Scalia's vacant seat.

Merkley's threats potentially set up another year of heated rhetoric over the court seat. Last year, Obama and Democrats repeatedly accused Republicans of playing politics by blocking Garland's nomination.

A filibuster would mean Trump's nominee would need 60 votes to get confirmed, and Republicans have 52 Senate seats. However, Democrats would risk Republicans ending the filibuster and losing it in future fights.

White House spokesman Sean Spicer slammed the potential filibuster move on Monday.

"Before they've even heard who this individual is, some of them are absolutely saying 'no.' That just shows this is all about politics," the press secretary said.

Senate Minority Leader Chuck Schumer, D-N.Y., previously indicated that he could oppose Trump's pick if he is not "mainstream."

Trump said he will announce the choice at 8 p.m. ET on Tuesday. Reports indicate he is considering Neil Gorsuch, a judge on the federal appeals court's 10th Circuit, and Thomas Hardiman, an appeals judge for the 3rd Circuit.