The U.S. Supreme Court has never ruled on Section 3 of the 14th Amendment, which was added after the Civil War to prevent former Confederates from returning to government.

The Colorado Republican Party on Wednesday appealed that state’s Supreme Court decision that found former President Donald Trump is ineligible for the presidency, the potential first step to a showdown at the nation’s highest court over the meaning of a 155-year-old constitutional provision that bans from office those who “engaged in insurrection.”

The first impact of the appeal is to extend the stay of the 4-3 ruling from Colorado’s highest court, which put its decision on pause until Jan. 4, the day before the state’s primary ballots are due at the printer, or until an appeal to the U.S. Supreme Court is finished. Trump himself has said he still plans to appeal the ruling to the nation’s highest court as well.