Donald Trump's 2024 election campaign says it will file a legal challenge to a ruling by the state of Maine to prevent him from contesting the Republican primary there. Maine is the second state to announce such a move after Colorado, with officials in both sighting a clause in the Constitution which bans those who have engaged in insurrection from taking political office. The US Supreme Court is likely to make the ultimate decision as to whether he can run for President. Live to Thomas Giff now, who is Director of the Center on US at the University College London. Good to see you. Can you explain to us what exactly this constitutional insurrection clause is?

Well, it's great to be with you, Lucy, as always. Essentially, Section 3 of says that individuals who have engaged in insurrection or rebellion are ineligible for running for president. Essentially, defenders of Donald Trump are going to say that this ruling by the main secretary of state is unconstitutional for a few reasons. One is that the provision requires that Congress do this and not individual states. Second, that the insurrection clause applies explicitly to officers of the United States, and that the President arguably doesn't qualify under that criteria. And then third, the Constitutional already sets out provisions for executive impeachment under Article Two Section 4. So the claim is that the 14th Amendment was never designed to substitute for that accountability mechanism.

Thomas, there's obviously some urgency now with it appearing before the Supreme Court. We could see other states following suit as well. How does that work in terms of the timing?

Well, practically, the Supreme Court has no choice. It has to take up this case because the worst possible outcome would be to have a scattershot process where Trump is ordered off the ballot in some states, allowed to stay on it in others, and all this confusion occurs against the backdrop of the primaries. If it's not ruled on, it could also create a layer of other complications. State Republican parties could say that they're going to circumvent these rulings by shifting from primaries to caucuses. That would require a waiver from the Republican National Committee, but it could also trigger lawsuits by state governments to prevent that change, which could be appealed. There's a real urgency to get this resolved, which is why the Supreme Court will expedite its review. My best guess is that we'll probably get an answer at the latest by Super Tuesday, which is March fifth. That's when Colorado and 15 or other so states are planning to hold their primaries.

Thomas, do you find it an interesting one for the Supreme Court? Because you've got Trump appointees there, but you've also got judges who are originalists. They literally do believe in the Constitution. This presents a bit of a challenge for them.

Well, it does. You could just look at the numbers and say six to three conservative to liberal, and three of those justices were appointed by Donald Trump. By default, essentially, he has the advantage, and I think that he does practically. You can get into these textualist arguments about what the constitution says, what it means. I do think that there are legitimate claims to be made on either side. I think if you want to look at one provision, it is this provision in the 14th Amendment that says that the Congress shall have power to enforce, by appropriate legislation, the provisions of this article. And what we saw in Colorado, what we saw in Maine is a state Supreme Court and a Secretary of state exercising this discretion. That's not Congress. I think that's why ultimately an originalist interpretation is going to come down on the side of Donald Trump. But there's still uncertainty and you never know.

It's always good to see you, Thomas. Thanks so much. Thank you. You can find much more on the US presidential election in a special section of our website. It's called a really simple guide, and you'll find everything you need to understand how the process works from getting chosen as a candidate to the debates and what it takes to win. So do log on and take a look.