Explainer-What's at stake in Trump's US Supreme Court bid to stay on Colorado ballot

By Andrew Chung

(Reuters) - The U.S. Supreme Court is set on Thursday to weigh Donald Trump's fight to stay on the ballot in Colorado in a case that carries high stakes not only for the former president, but also for the justices.

The justices are scheduled to hear arguments in Trump's appeal of the Colorado Supreme Court's Dec. 19 decision disqualifying him from the state's Republican presidential primary ballot based on language in the U.S. Constitution's 14th Amendment for engaging in insurrection, involving the Jan. 6, 2021, attack by his supporters on the U.S. Capitol.

Here is an explanation of the case.

What does the case mean for Trump and the court?

Trump is the frontrunner for his party's nomination to face Democratic President Joe Biden in the Nov. 5 U.S. election. With several challenges on 14th Amendment grounds cropping up, it is important for Trump's candidacy to clear any hurdles to appearing on the ballot in all 50 states. Maine also has barred him from its ballot, a decision put on hold pending the Supreme Court's ruling in the Colorado case.

For the Supreme Court, whose 6-3 conservative majority includes three Trump appointees, the case presents novel legal questions. Particularly if it is decided strictly along ideological lines, the justices face the risk of being painted as partisans. Not since ruling in the landmark case Bush v. Gore, which handed the disputed 2000 U.S. election to Republican George W. Bush over Democrat Al Gore, has the court played such a central role in a presidential race.

What is the constitutional provision at issue?

Six Colorado voters - four Republicans and two independents - filed suit in a bid to keep Trump off the state's ballot, invoking Section 3 of the 14th Amendment. This provision bars from office any "officer of the United States" who took an oath "to support the Constitution of the United States" and then "engaged in insurrection or rebellion against the same, or given aid or comfort to the enemies thereof." The amendment was ratified in the aftermath of the Civil War of 1861-1865 in which seceding Southern states that allowed the practice of slavery rebelled against the U.S. government.

What did the Colorado Supreme Court's decision say?

Colorado's top court decided that Trump, through his actions ranging from pressing false claims of widespread voter fraud to urging his supporters on Jan. 6 to march to the Capitol and "fight like hell," participated in the insurrection. It also decided that Trump aided "the insurrectionists' common unlawful purpose of preventing the peaceful transfer of power in this country."

What are Trump's arguments?

Among their key arguments, Trump's attorneys contend that he is "not subject to Section 3" because a president is not an "officer of the United States," a position they argue is instead typically appointed or commissioned by the president. They also contend that Section 3 cannot be enforced by courts absent congressional legislation, that it prohibits individuals from holding, but not running for, office, and that, in any event, Trump did not engage in an insurrection.

What are the plaintiffs' arguments?

The plaintiffs are led by 91-year-old Norma Anderson, a lifelong Republican and former Colorado state lawmaker. They have said that a president clearly 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." They also have said that Section 3, like other qualifications for office, may be enforced by states without federal legislation.

How will the justices handle the case?

When the justices decided to take up and fast-track Trump's appeal - a mere two days after he filed it - they did not winnow down the many legal questions swirling in the case. It remains unclear what they might focus on during oral arguments, but their questions may signal how they will resolve the dispute. Given that Colorado's presidential primary takes place on March 5, also known as "Super Tuesday," the justices could issue a ruling quickly.

(Reporting by Andrew Chung in New York; Editing by Will Dunham)