Mr Trump, 77, is expected to trounce Nikki Haley, his rival, and all but sew up the GOP nomination on Tuesday, when 15 states and one territory vote for who they want to take on Joe Biden in this year’s presidential election.
On Monday, the Supreme Court’s nine justices unanimously overturned an earlier decision to remove Mr Trump from Tuesday’s Colorado primary race over his role in the Jan 6 riot at the Capitol.
The court said it would be “incongruous” to give individual states the power to disqualify candidates for the presidency.
Minutes after the ruling was published, Mr Trump wrote on the Truth Social online site: “Big win for America!!!”
Speaking later from his Mar-a-Lago estate in Florida, he said the ruling would be remembered for 200 years and praised the Supreme Court for “working so quickly and so diligently and so brilliantly”.
He said: “The voters can take the person out of the race very quickly, but a court shouldn’t be doing that and the Supreme Court saw that very well, and I really do believe that will be a unifying factor.”
Buoyed by the ruling, Mr Trump added: “Super Tuesday is the big one and… we could clean it out.”
While Monday’s ruling is specific to Colorado, it will set a precedent for other states, including Illinois and Maine, which had also moved to bar him from the primary race.
The Supreme Court overruled the Dec 19 decision by Colorado’s top court to remove the former president from the state’s Republican primary ballot on the insurrection clause set out on Section 3 of the 14th Amendment of the US Constitution.
The provision was adopted after the Civil War in 1868 and was intended to keep former officeholders who “engaged in insurrection” from regaining power.
The Supreme Court concluded that while states can “disqualify” from state office, they have “no power under the Constitution to enforce Section 3 with respect to federal offices, especially the presidency”.
In a concurring opinion, the three Democrat judges said the Colorado ruling would “create a chaotic state-by-state patchwork, at odds with our nation’s federalism principles”.
Justices Sonia Sotomayor, Elena Kagan and Ketanji Brown Jackson said it would “defy logic” to give the states “new powers to determine who may hold the presidency”.
The Colorado Republican Party had requested that the Supreme Court make its judgment before Tuesday’s primary contest.
Jena Griswold, the Colorado Secretary of State, expressed disappointment at the ruling “stripping states of the authority” to enforce the disqualification clause, writing on social media: “Colorado should be able to bar oath-breaking insurrections from our ballot.”
Monday’s decision was largely expected after both Republican and Democrat judges expressed concern individual states having the power to decide the presidential election during last month’s two-hour court session.
