Rubio: I'm not getting cold feet on immigration

But Rubio has also made comments in recent days that some Senate insiders interpreted as an effort to distance himself from the controversial bill.

“He probably gets cold feet 20 times a day,” a senior Democratic aide said of Rubio.

“It’s a roller coaster and reflects the incoming [fire] he’s taking from his base when he goes home for a recess, but when he comes back to Washington he remembers he has partners,” said the aide. “I don’t think he’s going to take a walk.”

A source close to the Gang of Eight said Rubio is probably trying to distance himself somewhat from the bill to give House Republicans more leverage in negotiations with Senate Democrats. Republicans want to increase caps on work visas, especially for low-skilled workers, and staunchly oppose a proposal backed by Sen. Dick Durbin (D-Ill.), also a member of the Gang of Eight, to recognize same-sex and heterosexual couples equally.