It’s common for major presidential candidates, and even political parties, to have to address position changes. Political climates and orthodoxies can change rapidly. And some Rubio opponents are feeling even more heat than he is on this front right now.

But fending off flip-flopping charges could be especially thorny for Rubio, some Republicans say, since he is already defined heavily by immigration — an issue where his position now is not what it was as recently as 2013.

Mark Meckler, a leading tea party activist, said that whenever there is suspicion about whether Rubio’s views have changed, it could remind conservatives about his push for comprehensive reform and then his swift move away from it.

“I think it amplifies the immigration stuff,” said Meckler.