For a Republican presidential candidate it may be the ultimate insult: being compared to President Obama. 

South Carolina Senator Lindsey Graham slipped in a dig at Kentucky Senator Rand Paul Sunday while railing against the Obama administration's nuclear deal with Iran. Arguing that the United States should not accept the current framework for negotiations with Iran, Graham singled out Paul as the only presidential hopeful who would do worse than Obama. 

"The best deal, I think, comes with a new president. Hillary Clinton would do better. I think everybody on our side, except maybe Rand Paul, could do better," Graham said on CBS' Face The Nation.

The animosity between Graham, an interventionist on foreign policy matters, and Paul, who critics have dubbed an "isolationist," goes back a few years. In 2012, the two men waged what has come to be known as the "crazy bastard" fight on the Senate floor on the subject of whether to allow the detainees of Guantanamo Bay prison trials in the American court system.

In 2013, the feud continued to heat up, this time on the subject of the Obama administration's use of drones to target terrorism suspects.

Earlier this year, Graham again took aim at Paul, this time on the subject of vaccines. In an interview with CNBC, Paul stated that vaccines carried risks for children. 

"I have heard of many tragic cases of walking, talking normal children who wound up with profound mental disorders after vaccines," Paul asserted. 

That claim proved too much for Graham. 

"The statement of Paul would create anxiety because he's a doctor, he's a respected senator and there is no evidence that I'm aware of that a vaccine causes mental retardation," Graham told CNN. "If he has that evidence he should come forward and let the scientific community do something about it. You cannot scare people by anecdote."


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