A lesser-known clause in the U.S. Constitution could prohibit several candidates from being former President Donald Trump's running mate.

The 12th amendment, which was adopted in 1803, restricts electoral college voters from casting ballots from president and vice presidents from the same home state, which would eliminate Florida Sen. Marco Rubio, Rep. Byron Donalds and Gov. Ron DeSantis from consideration. Trump, a New York native, relocated to Florida in 2019 and acknowledged Rubio's "residency problem" while discussing the possibility of selecting him as a running mate via The Bulwark.

Trump previously named Donalds on his shortlist of potential running mates in February, though Donalds, himself, told the New York Post, "we can cross that bridge when we come back to it," while claiming he hadn't thought about the 12th amendment.

“I want to do everything to help win back the White House,” Donalds told the Post during the Conservative Political Action Conference in Maryland this week. “It’s about putting in the policies that work for the country and work for everybody.”

Earlier this week, Bloomberg reported that Trump arrowed down his running mate options to four candidates, which included Rubio after teasing a timeline for his decision this week. Other reported options included Gov. Doug Burgum, as well as Sens. JD Vance of Ohio and Tim Scott of South Carolina, though senior adviser Brian Hughes pushed back at the claim in a statement obtained by the New York Post.

"Anyone claiming to know who or when President Trump will choose his VP is lying, unless the person is named Donald J. Trump," Hughes said.

Trump said that he would reveal his running mate decision at some point "not too much before" the Republican National Convention, which is scheduled to be held in Milwaukee from July 15-18, while speaking to FOX 6 Milwaukee during a campaign visit to the state on Wednesday (May 1).

Armstrong & Getty