U.S. Sen. Marco Rubio is reportedly in the mix to serve as Donald Trump’s running mate, but tapping a fellow Floridian for the job could mean running afoul of a rarely invoked constitutional provision.

The debate centers around a clause in the 12th Amendment of the U.S. Constitution, which says that electors cannot vote for both a president and vice president from their own state. Taken at face value, that would prevent Florida’s 30 presidential electors from voting for a hypothetical Trump-Rubio ticket.

NBC News first reported on Wednesday that Rubio is under consideration for the Republican VP slot, though Trump has said that he’s weighing more than a dozen potential picks. Still, Rubio would be a notable choice. A Miami native and the son of working-class Cuban immigrants, Rubio would be the first Hispanic candidate on a major party’s presidential ticket.

Rubio also has a winning track record in Miami-Dade County, a majority Hispanic and vote-rich part of Florida that Trump and his allies are eager to carry in the November election.

Yet if Trump, who officially became a Florida resident in 2019, ultimately names Rubio as his running mate, the fact that they share a home state would likely draw scrutiny.

What’s the issue?

Kevin Wagner, a political science professor at Florida Atlantic University, said that there’s actually nothing in the Constitution preventing presidential and vice presidential candidates who reside in the same state from running together.

He acknowledged that the language in the 12th Amendment was “a bit unclear” but noted that the prohibition applies only to electors casting both their presidential and vice presidential votes for two candidates from the same state as the elector.

“Contrary to popular opinion, it’s not actually unconstitutional for two persons from the same state to run together,” Wagner said.

But, he noted, “it does create a little bit of a problem when the electoral college casts its vote.”

“[The electors] aren’t allowed to vote for two people from the same state that they come from, so hypothetically you couldn’t vote for both Mr. Trump and Mr. Rubio, or at least the Florida electors couldn’t,” Wagner said. “If a hypothetical ticket of Trump-Rubio won by enough of a margin though it wouldn’t matter.”

What about the courts?

The debate over the 12th Amendment’s so-called “Habitation Clause” came up briefly in the 2000 presidential election, when then-Republican candidate and Texas Gov. George W. Bush tapped Dick Cheney as his running mate.

Cheney, who also lived in Texas, changed his state of residency to Wyoming — where he had previously served as a congressman — just days before Bush chose him for the ticket. Three Texas residents challenged Cheney’s residency in federal court, but an appeals court dismissed the case before the U.S. Supreme Court declined to hear it.

“When the challenge was brought on the question of the residency, it didn’t seem that the courts had much of an appetite to adjudicate,” Wagner said.

Pack a bag?

If Trump chooses Rubio as his running mate, either he or the senator could choose to take a page out of the Bush-Cheney playbook and switch his state of residency, though Wagner noted that would be particularly difficult for Rubio given that he’s a federal office holder in Florida.

Spokespeople for Trump and Rubio did not respond to the Miami Herald’s requests for comment on the running mate considerations and whether they would consider leaving Florida.

Even if Trump ultimately taps Rubio to be his running mate, it’s unclear if the senator would accept. He told NBC News on Thursday morning that it would be an “honor” to serve as vice president, though he also said that he hasn’t spoken to Trump or anyone in the former president’s orbit about it.

Rubio also has national political ambitions, as evidenced by his unsuccessful 2016 bid for the Republican presidential nomination.

But he’s expressed hesitation before about serving as Trump’s running mate. In an interview with Fox News in January, Rubio appeared to throw cold water on the idea, raising the debate over the 12th Amendment.

“Well, we’re both from the same state, so that’s probably not going to work that way,” Rubio said at the time.