It looks like a remarkable situation is brewing in respect of Tennessee. The legislature there is trying to outlaw from running for Congress a candidate who has been endorsed by President Trump. It looks like some of the measure’s backers might be Democrats scared of the former president. The measure, though, was launched by Republicans, some of whom apparently favor another pro-Trump candidate.

So put that in your Jack Daniel’s, with a splash of the Constitution.

This arises after the legislature in the Volunteer State passed a law requiring candidates for congress to have resided for three years in the district in which they’re running. The measure, according to the Tennessean newspaper, “implicitly” targets “the candidacy of Morgan Ortagus.” She is an ex-spokeswoman of the State Department who is bidding to run for Congress on the Republican line in Tennessee’s 5th District.

The residency requirement bill, according to the Tennessean, “bubbled up” in the state’s General Assembly “shortly after Ortagus bagged an early endorsement from former President Donald Trump, who praised the Fox News commentator for her work at the State Department during his administration.” The measure passed the Republican-controlled state legislature on a bipartisan vote, with only one dissenter in the Senate.

Politico is reporting that Mr. Trump’s endorsement of Ms. Ortagus is triggering a “MAGA revolt” among some of the former president’s own loyalists, who favor Robby Starbuck, “a rival candidate who’s been a mainstay of the pro-Trump movement.” Politico calls it a “serious backlash.” It quotes one conservative activist, Daniel Bostic, as calling the contretemps a “watershed moment” for the Trump team.

What draws our attention, though, is the constitutional question, over which litigation has reportedly already begun. The focus is whether a state can add to the list of qualifications for a candidate running for Congress hurdles that are not listed in the Constitution itself. This reached the Supreme Court in the mid-1990s, when Arkansas tried to impose a limit on the number of terms members of its delegation could serve.

The Nine, in a case called U.S. Term Limits Inc. v. Thornton, struck down the restrictions. The justices held that “the Constitution prohibits States from imposing congressional qualifications additional to those specifically enumerated in its text.” That would seem logical given the parchment’s Supremacy Clause, which makes the Constitution, federal laws, and ratified treaties the “supreme law of the land.”

Yet from a distance of 25 years the thing that strikes us about Thornton is how closely divided the court was — and along ideological lines. The majority comprised the liberals, Associate  Justices John Paul Stevens, Stephen Breyer, and Ruth Bader Ginsburg, plus two centrists, Associate Justices David Souter and Anthony Kennedy. The dissenters were all the conservatives, Chief Justice Rehnquist, along with Associate Justices Clarence Thomas, Sandra Day O’Connor, and Antonin Scalia.

That lineup of sages has nagged at us for years. The dissent was written by Justice Thomas, who declared: “Nothing in the Constitution deprives the people of each State of the power to prescribe eligibility requirements for the candidates who seek to represent them in Congress. The Constitution is simply silent on this question. And where the Constitution is silent, it raises no bar to action by the States or the people.”

All three of the justices who joined Justice Thomas in that dissent are, sadly, gone now. Yet standing on their shoulders is a new and vibrant conservative majority on the court, led by Justice Thomas himself. It’s way too soon to know how far, if at all, the litigation now stirring in Tennessee might be pressed. It’s not too soon, though, to wonder whether the court could eventually overturn Thornton and let the states set their own rules for the qualifications of their members of Congress.