The gloves are off. Two possible contenders for the 2016 Republican presidential nomination are taking shots at one another by name over their respective stances on the Obama administration’s decision to begin to normalize relations with Cuba.

Sen. Rand Paul (R-KY), who voiced support for easing restrictions on Cuba Thursday, took to Facebook Friday to attack Sen. Marco Rubio (R-Fl) — a vocal critic of the move — as an “isolationist who wants to retreat to our borders and perhaps build a moat.”

“Senator Marco Rubio believes the embargo against Cuba has been ineffective, yet he wants to continue perpetuating failed policies,” Paul wrote.

“After 50 years of conflict, why not try a new approach?” he continued in his post Friday. “The United States trades and engages with other communist nations, such as China and Vietnam. Why not Cuba? I am a proponent of peace through commerce, and I believe engaging Cuba can lead to positive change.”

Paul has set himself apart from possible 2016 GOP presidential prospects this week with his Cuba stance.

While Rubio, former Florida Gov. Jeb Bush, and Sen. Ted Cruz (R-FL) have attacked the administration’s move, Paul has expressed an openness to the idea, with preconditions for the Cuban regime.

“I reject this isolationism,” Paul wrote Friday. “Finally, let’s be clear that Senator Rubio does not speak for the majority of Cuban-Americans. A recent poll demonstrates that a large majority of Cuban-Americans actually support normalizing relations between our countries.”

Thursday evening on Fox News’s “The Kelly File” Rubio told host Megyn Kelly that Paul “has no idea what he’s talking about” on Cuba.