Denver, Colorado - A conservative legal group has filed an appeal against the decision by the Colorado Supreme Court that disqualified Donald Trump from next year's presidential primary in the state.

American Center for Law and Justice (ACLJ) said on Wednesday it was challenging the court's decision on behalf of the Republican Party of Colorado. It is seeking the US Supreme Court to overturn the ruling.

"This is the greatest election interference case in US history and represents a grave attack on millions of Americans’ fundamental right to vote," said the ACLJ in a statement.

State-by-state primary voting begins in January with Iowa. These primary elections determine who will be on the ballot for the general election on November 5.

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Last week, the Colorado Supreme Court ruled that Trump was ineligible for the March 5 state primary due to his role in the storming of the US Capitol in Washington on January 6, 2021 and could not participate in the primary election.

The 77-year-old hopes to win the 2024 presidential election and return to the White House, but his opponents are trying to have his name removed from the ballot in several states.

Trump's opponents are arguing on the basis of the Constitutions 14th Amendment, which excludes from public office people who have instigated a "rebellion" against the constitution. So far, they have only been successful in Colorado.

Trump had announced an appeal against the judgement in Colorado, but has not yet lodged one. The Colorado Supreme Court has itself stayed its decision until the issue has been finally clarified in the event of an appeal.