The Supreme Court ruled on Monday that states may not bar former President Donald J. Trump from running for another term, rejecting a challenge from Colorado to his eligibility that threatened to upend the presidential race by taking him off ballots around the nation.

Though the justices provided different reasons, the decision’s bottom line was unanimous. All the opinions focused on legal issues, and none took a position on whether Mr. Trump had engaged in insurrection, as Colorado courts had found.

All the justices agreed that individual states may not bar candidates for the presidency under a constitutional provision, Section 3 of the 14th Amendment, that prohibits insurrectionists from holding office. Four justices would have left it at that, with the court’s three liberal members expressing dismay at what they said was the stunning sweep of the majority’s approach.

But the five-justice majority, in an unsigned opinion answering questions not directly before the court, ruled that Congress must act to give Section 3 force.

“The Constitution makes Congress, rather than the states, responsible for enforcing Section 3 against federal officeholders and candidates,” the majority wrote, adding that detailed federal legislation was required to determine who was disqualified under the provision.

The decision was produced on a rushed schedule, landing the day before the Super Tuesday primaries in Colorado and around the nation. In a series of unusual moves, the court did not announce that it would issue an opinion until Sunday and did not take the bench to do so on Monday, instead simply posting the decision on its website.