“He was not only totally committed — he was in that room with us, four Democrats, four Republicans,” Schumer told CNN Thursday in an interview in his Senate office. “His fingerprints are all over that bill. It has a lot of Rubio imprints.”

Schumer, the next Senate Democratic leader, painstakingly hashed out the immigration deal with Rubio and has previously avoided lashing out at the Florida Republican publicly. But as the presidential race heats up, Schumer is unloading the new line of criticism, saying Rubio was the main architect of the provision to provide a pathway to citizenship for the nation’s 11 million undocumented immigrants, something bound to give ammunition to his primary foes who call the measure “amnesty.”

“He understood it, he molded it, he made it a tough path to citizenship,” Schumer said. “But we all agreed to it, and it would have to be a tough path to citizenship. But he was all for it. “