Former U.S. President Donald Trump’s latest round of court battles opens a new legal front and tests an arcane constitutional provision preventing insurrectionists from holding political office.

Pressure is mounting on the U.S. Supreme Court to decide whether states can bar Trump, who is the Republican party’s leading candidate, from the ballot. The case would be unprecedented and brings Trump’s conduct after losing the 2020 election back to the forefront of his likely 2024 rematch with President Joe Biden.

On Thursday, Maine’s top election official blocked Trump from the ballot, citing his actions related to the riot at the U.S. Capitol on Jan. 6, 2021. That ruling followed a groundbreaking decision in Colorado last week declaring him ineligible to be on the ballot there.