The elbow throwing has already begun between Republican hopefuls looking to run for president in 2016. In the second time in as many days, the Campaign for Liberty, which is chaired by former Texas Congressman Ron Paul, attacked U.S. Sen. Marco Rubio, R-Fla., for voting against an amendment from a possible 2016 rival -- U.S. Sen. Rand Paul, R-Ky., the son of the groups chairman.