(CNN) -- Sen. Marco Rubio and Sen. Rand Paul traded barbs on Friday over their divergent opinions on the Obama administration's move to normalize relations with Cuba.
On Wednesday, Paul a rare figure on the Right speaking out in support of the move to relax the decades-long embargo on Cuba and open up an embassy there. And on Thursday night, Rubio — one of the GOP's most outspoken critics of the policy shift — knocked the Kentucky Senator.
"Like many people that have been opining, he has no idea what he's talking about," Rubio on Fox News' "The Kelly File."
But Paul lashed back out on Twitter on Thursday, accusing Rubio of being an "isolationist" — a charge he himself has faced, as a libertarian in a traditionally hawkish party.
Paul went on:
And he pointed to a June poll that showed most Cuban-Americans oppose the trade embargo on Cuba.
While Rubio has slammed the move to restore diplomatic relations with Cuba as misguided and pledged to work to prevent it in the Senate, Paul called it a "good move."
"The 50-year embargo with Cuba just hasn't worked," Paul said in an interview with West Virginia radio station WVHU. "If the goal is regime change, it sure doesn't seem to be working and probably it punishes the people more than the regime because the regime can blame the embargo for hardship."
And he was the only potential GOP presidential contender to express support. Former Florida Gov. Jeb Bush and Sen. Ted Cruz of Texas have both come out opposed, and Rubio's been one of the president's fiercest critics on the right.
Paul's support for ending the embargo comes as little surprise, however, as it aligns with his libertarian beliefs. Indeed, his father, former Rep. Ron Paul, introduced a bill to lift the embargo during his time in Congress.
But it highlights one of the first major policy divides confronting the developing GOP presidential field, and Rubio's response hints at more infighting to come — exactly the outcome many in the party have feared would arise from a wide-open and protracted primary fight.