Sen. Rand Paul, R-Ky., believes Gov. Chris Christie might have a problem if he runs for president in 2016 because the New Jersey Republican supported an expansion of Medicaid in his state.

Paul said Christie's Medicaid decision was more in line with the Democratic Party than with a moderate Republican.

"That's not really even close to the center of the Republican Party," Paul said on Fox News. "It's more close to what Democrat governors did."

There is plenty of room for moderates in the Republican Party, the Kentucky senator said, but he expects them to have difficulties in the presidential primaries.

"Accepting Obamacare, and expanding it, bringing it to your state, I don't think that is going to resonate in the Republican primary. We're pretty conservative in the Republican primary." Paul said. "So, we'll see."

A number of Republican governors have supported the Medicaid expansion included in Obamacare. Among them are Brian Sandoval of Nevada, Jack Dalrymple of North Dakota, Rick Scott of Florida, John Kasich of Ohio, Rick Snyder of Michigan, Susana Martinez of New Mexico and Jan Brewer of Arizona.

Republican governors who have opposed Medicaid expansion include potential 2016 presidential candidates Scott Walker of Wisconsin, Bobby Jindal of Louisiana and Rick Perry of Texas.