Former US president Donald Trump has asked the US Supreme Court to intervene after Colorado’s top court disqualified him from the state’s Republican primary ballot.

Trump, the frontrunner for the Republican 2024 presidential nomination, is contesting the December 19 Colorado Supreme Court decision that disqualified him under a constitutional provision barring anyone who “engaged in insurrection or rebellion” from holding public office.

Trump was barred over his actions ahead of the January 6 attack on the US Capitol.

The Colorado court had already put its decision on hold until January 4, stating that Trump would remain on the ballot if he appealed.

Trump’s filing on Wednesday (US time) places a politically explosive case before the nation’s highest judicial body, whose 6-3 conservative majority includes three of his own appointees. The justices’ action will shape a wider effort to disqualify Trump from other state ballots as the 2024 US presidential election draws closer.

The attack on January 6, 2021, was an attempt by Trump’s supporters to overturn his 2020 election loss to Democratic President Joe Biden, which Trump falsely claims was the result of fraud.

The Colorado court’s historic ruling marked the first time in history that section three of the US Constitution’s Fourteenth Amendment – the so-called disqualification clause – had been used to deem a presidential candidate ineligible for the White House.

Trump has also appealed to a Maine state court a decision by that state’s top election official barring him from the primary ballot in that state under the same constitutional provision at issue in the Colorado case.

The ruling came in a lawsuit filed by Republican and unaffiliated voters, and backed by watchdog group Citizens for Responsibility and Ethics in Washington. It sought to bar Trump from the nominating primary and future elections under the disqualification clause.

Section three bars 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” from holding office.

The amendment was ratified in the aftermath of the American Civil War of 1861-1865, in which southern states rebelled in a bid for secession.

The 4-3 Colorado Supreme Court ruling reversed a lower court judge’s conclusion that Trump engaged in insurrection by inciting his supporters to violence, but as president, he was not an “officer of the United States” who could be disqualified under the Fourteenth Amendment.

The Colorado court concluded Trump’s role in instigating violence at the Capitol as lawmakers met to certify the results of the 2020 election constituted engaging in insurrection, and that the presidency is covered by the insurrection provision.

“President Trump asks us to hold that section three disqualifies every oath-breaking insurrectionist except the most powerful one and that it bars oath-breakers from virtually every office, both state and federal, except the highest one in the land. Both results are inconsistent with the plain language and history of section three,” the majority wrote.

Acknowledging the magnitude of the case, the majority said, “We are likewise mindful of our solemn duty to apply the law, without fear or favour, and without being swayed by public reaction to the decisions that the law mandates we reach.”

Trump’s lawyers argued that his speech to supporters on the day of the riot was protected by his right to free speech, adding that the constitutional amendment does not apply to US presidents and that Congress would need to vote to disqualify a candidate.

Courts have rejected several lawsuits seeking to keep Trump off the primary ballot in other states. Minnesota’s top court rebuffed an effort to disqualify Trump from the Republican primary in that state but did not rule on his overall eligibility to serve as president.

-AAP