Four GOP senators are trying to gain the upper hand on the commander-in-chief test — Marco Rubio, Rand Paul, Ted Cruz and Lindsey Graham — and their competition was on vivid display as the Senate took up a Rubio plan to pump tens of billions of dollars more into the Pentagon budget. Paul blasted the idea because the new spending wasn't offset by other cuts. And caught in the middle was Cruz, who's pitching himself as a fiscal conservative who can appeal to the hawkish and libertarian wings of the GOP but ultimately sided with Rubio and Graham.

In an interview with POLITICO, Paul lambasted his foes for engaging in "reckless" and "irresponsible" behavior, showing that they lacked the "courage" and conviction to rein in the country's mountain of debt. He said there are now two camps in the GOP primary field: one that cares about the debt, and another that does not.

"I think there are a great deal of problems for people who want to argue that they are fiscal conservatives and yet would simply borrow hundreds of billions of dollars for defense," Paul said. "I think it is irresponsible and dangerous to the country to borrow so much money to add into defense."