Rand Paul: Jeb Bush is not conservative enough

The Republican battle over what constitutes being a true conservative is well under way.

Rand Paul fired a shot Wednesday on MSNBC's Morning Joe, saying he doesn't believe former Florida Gov. Jeb Bush is conservative enough to be the Republican nominee in 2016.

"I seriously doubt it," the first-term Kentucky senator. "I think he’s going to have trouble. I think he has trouble on two fronts -- one, getting the nomination and convincing conservatives that he’s conservative."

Paul, who is on a media tour promoting a new book, also cited the record of President George W. Bush -- Jeb's brother -- and the Iraq war.

Jeb's "second problem will be the Bush legacy on war will destroy any hope we have of getting an Independent vote," Paul said.

Other Republicans have also questioned Bush's commitment to conservatism, citing immigration and Common Core education standards among other issues.

Bush, meanwhile, says his two terms in Florida provided a model of conservative governance, including lower taxes and spending cuts.

In the MSNBC interview, Paul added that his libertarian-leaning conservatism would play better in independent states against probable Democratic opponent Hillary Clinton.

"If you look at me in the purple states, I’m the only one that beats Hillary Clinton in Colorado, Iowa, Pennsylvania, and New Hampshire," Paul said.

Other Republicans, meanwhile, say Paul's conservatism is out of the mainstream, especially on foreign policy. Sen. Lindsey Graham, R-S.C., and other Republicans call Paul an isolationist whose approach would embolden the Islamic State (ISIS) and other terrorist groups.

Paul flipped that analysis on Morning Joe.

"ISIS exists and grew stronger because of the hawks in our party who gave arms indiscriminately," Paul said. "And most of those arms were snatched up by ISIS."