(NewsNation) — The Supreme Court heard oral arguments Thursday on an effort by former President Donald Trump to reverse a ruling by Colorado’s top court barring him from the state’s 2024 Republican presidential primary ballot.

The nine justices, three of whom Trump appointed, will hear arguments from Trump’s appeal of a decision by the Colorado Supreme Court. In December, Colorado’s top court decided that Trump engaged in the Jan. 6, 2021, U.S. Capitol insurrection and therefore should be disqualified from appearing on a ballot under Article III of the U.S. Constitution’s 14th Amendment.

A crucial portion of that section reads: “No person shall hold any office, civil or military, under the United States who, having previously taken an oath to support the constitution of the United States, shall have engaged in insurrection or rebellion against the same.”

Concerns included whether Congress must act before states can invoke a constitutional provision that was adopted after the Civil War to prevent former officeholders who “engaged in insurrection” from holding office again. There also were questions about whether the president is covered by the provision.

Without such congressional legislation, Justice Elena Kagan was among several justices who wanted to know “why a single state should decide who gets to be president of the United States.”

Chief Justice John Roberts worried that a ruling against Trump would prompt efforts to disqualify other candidates, “and surely some of those will succeed.”

Trump is not expected to be present at the arguments scheduled for 10 a.m. ET. Instead, he plans to start his day at his Florida home and travel to Nevada, according to a source familiar with his plans.

The plaintiffs who filed the lawsuit seeking to disqualify Trump — four Republican voters and two unaffiliated voters — have said a president is an “officer of the United States” because “it would make no sense to read Section 3 as disqualifying all oath-breaking insurrectionists except the one holding the highest office in the land.”

Jonathan Mitchell, Trump’s lead lawyer, argues that the former president didn’t lead an insurrection and asserts that the section in question doesn’t apply to Trump, writing, “President Trump never told his supporters to enter the Capitol, and he did not lead, direct, or encourage any of the unlawful acts that occurred at the capitol. Giving a passionate political speech and telling supporters to metaphorically “fight like hell” for their beliefs is not insurrection either.”

The case calls on the Supreme Court to play a central role in a presidential contest unlike any since its landmark Bush v. Gore decision that handed Republican George W. Bush the presidency over Democrat Al Gore in 2000.

The Supreme Court’s ruling is expected to significantly impact cases across other states seeking to bar Trump from the ballot under similar grounds. Alongside Colorado, Maine has also deemed Trump ineligible and there are pending cases in California, Texas and New York.

The court could issue the decision shortly after Thursday’s arguments, as it has done in previous election-related cases such as Bush v. Gore, where it ruled just one day after the hearing.

Reuters contributed to this story.

The Associated Press contributed to this report.