National Harbor, Maryland (CNN) Don't chalk Rand Paul up as a libertarian just yet.

Gary Johnson, the Libertarian Party's 2012 presidential nominee, said the Republican senator from Kentucky is just that -- a Republican -- but definitely not a libertarian.

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While Paul may be the most libertarian-minded candidate in the field of prospective GOP presidential candidates, Johnson said, Paul doesn't fit the libertarian mold on a host of issues: from abortion to marriage equality to immigration and marijuana.

"He's a Republican," Johnson said.

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