“He is a man who has dedicated his public service to making sure government listens to the American people,” said Maria Strollo Zack, who has launched a super PAC urging Cruz to run, called Stand for Principle. “He’s not going to be bullied, he’s not going to be told to sit down and shut up.”

But while Cruz may have the early momentum with these activists, the broader battle for support among GOP activists will be one of the fiercest of the 2016 cycle. And many Republicans question how much appeal Cruz has beyond the most conservative faction of the GOP.

The senator himself acknowledged that popularity among the tea party alone isn’t enough to cinch the Republican nomination.