By Andrew Goudsward

Lawyers representing a group of Colorado voters are set to deliver closing arguments on Wednesday in a lawsuit seeking to disqualify former President Donald Trump from the state's ballot next year over his role in the Jan. 6, 2021, attack on the U.S. Capitol by his supporters.

The voters are seeking to use the U.S. Constitution's 14th Amendment, which bars officials who have engaged in "insurrection or rebellion" from holding public office, to argue that Trump is ineligible to run for president in 2024. The provision was ratified in 1868 following the U.S. Civil War.

The case represents a test of legal efforts to use the 14th Amendment to block Trump's candidacy. It is the first such case to go to trial.

The voters, represented in the case by the watchdog group Citizens for Responsibility and Ethics in Washington (CREW), sued Colorado's secretary of state, the state's top elections official, in a bid to block Trump's inclusion on the ballot. Trump is the frontrunner for the Republican nomination to challenge Democratic President Biden in the 2024 U.S. election.

Lawyers in the case on Wednesday will make their final pitch to Colorado District Court Judge Sarah Wallace, who will decide the case, following a weeklong trial that featured testimony from U.S. lawmakers, legal experts and Republican political operatives.

Thousands of people stormed the Capitol in a failed attempt to prevent Congress from certifying Biden's 2020 victory over Trump. The lawyers for the voters have sought to convince the judge that Trump's actions in spreading false claims of voter fraud, summoning his supporters to Washington on the day of the riot and initially refusing pleas to quell the violence amounted to an insurrection.

Trump's lawyers have denied that he incited his supporters to violence and have argued that disqualifying him from the ballot would set a dangerous precedent.

Colorado is regarded as a safely Democratic state by nonpartisan election forecasters. Regardless of whether Trump is on the ballot, Biden would be expected to win there. But CREW and other activists are seeking to bring a series of legal challenges to Trump's eligibility based on the 14th Amendment language.

Courts in Michigan and Minnesota have ruled that Trump can remain on the ballot for the Republican primaries in those states, but declined to immediately decide on his eligibility for the November 2024 general election.

The cases raise several unsettled legal questions. Many experts view the effort as a legal longshot. The U.S. Supreme Court, whose 6-3 conservative majority includes three Trump appointees, may ultimately weigh in.

(Reporting by Andrew Goudsward in Washington; Editing by Will Dunham and Scott Malone)