The U.S. Supreme Court on Monday unanimously ruled that former President Donald Trump can't be excluded from Colorado's primary election ballot because of his actions surrounding the Jan 6, 2021, attack on the U.S. Capitol.

The justices said the Constitution doesn't permit a single state to disqualify a presidential candidate from national office, ruling that such responsibility "rests with Congress and not the states".

"Because the Constitution makes Congress, rather than the States, responsible for enforcing Section 3 against federal officeholders and candidates, we reverse," the justices wrote.

The justices issued their decision one day before Super Tuesday, when Colorado and more than a dozen others hold primary contests for the November presidential election. The ruling applies to other states with similar challenges to Trump's candidacy.

The court's decision was expected because during oral argument in February, nearly all of the justices signaled skepticism of Colorado's authority to remove Trump from the ballot. They worried about the chaos it would cause if states had the unilateral authority to determine a candidate had engaged in insurrection and worried it could result in a chaotic, partisan tit-for-tat.

Trump wrote on his social media platform, Truth Social, "BIG WIN FOR AMERICA!!!"

Speaking at his Mar-a-Lago resort in Florida, Trump praised the decision as historic, "something that will be spoken about 100 years from now and 200 years from now".

Voters can eliminate candidates "very quickly, but a [state] court shouldn't be doing that, and the Supreme Court saw that very well," Trump said. "I think it will go a long way to bringing our country together, which our country needs."

Trump had appealed the Colorado Supreme Court's decision to disqualify him under the 14th Amendment's Section 3, the so-called insurrection clause of the Constitution. The court acted on a lawsuit filed by a group of Republican and independent voters.

It is the first time that the Supreme Court has weighed in on the insurrection clause.

Enacted after the civil war in 1868, the measure says that any member of Congress or officer of the United States who engages in insurrection after taking an oath to the Constitution is barred from holding office. It has never been used to bar a presidential candidate from office.

Trump has been charged with numerous federal and state felonies over his effort to keep power after losing the 2020 election, but he hasn't been indicted on the specific federal crime of insurrection, which carries a maximum sentence of 10 years and an automatic ban on holding federal office.

"Nothing in the Constitution requires that we endure such chaos — arriving at any time or different times, up to and perhaps beyond the inauguration," the court said in an unsigned, 13-page unsigned opinion.

The court's three liberal members suggested that the majority had gone too far in the decision and unnecessarily insulated Trump "from future controversy".

That prompted Justice Amy Coney Barrett, a Trump appointee who also didn't embrace all of the decision, to emphasize that the court had come together on the bottom-line outcome.

"That is the message Americans should take home," she wrote.

Barrett wrote that she hopes Americans will look to the decision and see common ground, not divisiveness.

"The Court has settled a politically charged issue in the volatile season of a presidential election. Particularly in this circumstance, writings on the Court should turn the national temperature down, not up. For present purposes, our differences are far less important than our unanimity: All nine Justices agree on the outcome of this case. That is the message Americans should take home."