House Speaker Mike Johnson announced that House Republicans will advance a constitutional amendment permanently limiting the Supreme Court to nine justices.

Johnson said the proposal is intended to prevent future efforts to expand the court for political purposes. “They want to pack the U.S. Supreme Court,” Johnson told reporters, adding that Republicans would bring the measure to the House floor to “make sure that doesn’t happen.”

The proposal comes after renewed calls from some Democratic lawmakers to increase the number of Supreme Court justices. Former Vice President Kamala Harris said in July that the court should be expanded from nine to 13 justices, while Rep. James Clyburn, D-S.C., recently expressed support for a 13-member court.

The Constitution does not currently specify how many justices must serve on the Supreme Court, leaving Congress with authority to establish the court’s size through federal law. Congress has changed the number of seats several times throughout American history. The court has remained at nine justices since 1869.

The effort would require a significantly higher threshold than an ordinary bill. A constitutional amendment must receive approval from two-thirds of both the House and Senate before being sent to the states. It would then need to be ratified by three-fourths of the states to become part of the Constitution.

Johnson’s proposal faces an uncertain path forward. House Democratic leaders have criticized the measure as a political maneuver, while Democratic lawmakers have continued to debate potential changes to the Supreme Court.

The proposal is also rooted in a long-running national debate over the independence and composition of the judiciary. President Franklin D. Roosevelt’s 1937 attempt to expand the Supreme Court failed after facing opposition in Congress.