A Republican-backed Senate rule change expected on Thursday could make it more likely that presidents will pick ideologically extreme U.S. Supreme Court nominees with little incentive to choose centrist justices, experts said.

With a deep partisan divide in Washington, Democrats are using a procedural tactic called a filibuster to try to block confirmation of President Donald Trump's Supreme Court nominee Neil Gorsuch in the Republican-led Senate.

Majority Leader Mitch McConnell has threatened to change long-standing rules in the 100-seat Senate in order to prohibit the tactic against Supreme Court nominees if the Democrats succeed with the filibuster. That would mean nominees could be confirmed by a simple majority rather than needing to first muster a 60-vote super-majority.