UNITED STATES Ã NOVEMBER 17: From left, Sen.-elect Rand Paul, R-Ky., and Sen.-elect Marco Rubio, R-Fla., leave the Mansfield Room during a break in freshman orientation on Wednesday, Nov. 17, 2010. (Photo By Bill Clark/Roll Call)

A dispute between two possible presidential candidates escalated on Friday around the topic of newly opened diplomatic relations with Cuba, and the latest jabs took place on -- where else -- the Internet.

Sen. Rand Paul (R-Ky.) took to Twitter and Facebook to lambaste Sen. Marco Rubio (R-Fla.), who claimed Thursday on Fox News that his fellow Senate Foreign Relations Committee member "has no idea what he's talking about" on Cuba. Paul came out in support of the Obama administration, which reached a historic accord with the communist island that included the release of U.S. Agency for International Development worker Alan Gross.

"The United States trades and engages with other communist nations, such as China and Vietnam. Why not Cuba?" the Kentucky Republican wrote on Facebook. "I am a proponent of peace through commerce, and I believe engaging Cuba can lead to positive change."

"Seems to me," Paul continued, "Senator Rubio is acting like an isolationist who wants to retreat to our borders and perhaps build a moat. I reject this isolationism. 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."

Rubio, who is the son of Cuban immigrants, loudly protested the shift in policy all week. He chided the president on Wednesday for "coddling dictators and tyrants" and for dealing with a regime that has "harassed, imprisoned and even killed" its own people.

The spat highlights a fissure in the Republican party, and is a sign of things to come should both senators decide to run for the White House. But it's not the first time the two have tangled over foreign policy. Last year, Rubio delivered a speech in Paul's home state in which he passionately made the case against isolationism -- a philosophy the libertarian senator from Kentucky has flirted with in the past.

At this rate, we may as well just cancel the debates.

UPDATE: Rubio responded in a Friday night interview with Mark Levin.

“I think it’s unfortunate that Rand has decided to adopt Barack Obama’s foreign policy on this matter,” he said.

“So you have these people coming out and saying, ‘Well maybe we should try something different,’” Rubio added. “And that’s what basically Rand did, he repeated the talking points of the president. And that’s fine, he has every right to support the president’s foreign policy if that’s where he wants to line up with. But I’m telling you, it isn’t going to work. This notion that somehow by doing this there's going to be change in Cuba is just not true. On the contrary, it's just going to strengthen the regime."

Rubio also criticized the president for apologizing to Cuba over "American colonialism," and suggested that ideology was a motivating factor in dealing with the Castro regime.