Tea Party Patriots’ other cofounder Marc Meckler, now president of Citizens for Self-governance, argued that “it’s hard to legitimately call Rubio ‘establishment’ when he beat down the establishment to take out Charlie Christ. Rubio’s voting record in the Senate and the stands he has taken there generally comport with tea party values.”

But Mr. Meckler then recounted his observations of what may be a growing rift between Mr. Rubio and the tea party, which much of the regular GOP and, more harshly, Republican operatives like Karl Rove have blamed for helping nominate conservative GOP candidates over more moderate ones who then get trounced by Democrats in general elections.

“I was in Florida last week for three days meeting with tea party groups, and I cannot tell you that Rubio is universally loved in the tea party movement,” Mr. Meckler said. “There is genuine skepticism, as many told me that he has kept his distance from, and been generally inaccessible to the tea party groups there.”