He threw down the gauntlet Sunday when he appeared opposite Ryan on CBS’s “Face the Nation” to urge House Republicans to vote against the rule that would bring the healthcare reform bill to the floor.

The audacious move surprised some lawmakers because voting on the rule, which sets the terms for debating and amending a measure, is viewed as a key test of loyalty to House leadership, which expects complete unity on such procedural steps. It’s all the more galling for the House GOP leadership that it’s a senator who’s playing hardball on their turf.

It’s a flashback to 2013, when Cruz, then a first-year senator, wielded his relationships with House conservatives to pressure GOP leaders to hold up a must-pass government funding bill to protest the implementation of ­ObamaCare.

“That’s what Cruz did a few years ago,” said a Republican senator who requested anonymity to candidly comment on Paul’s tactics.