Attorneys for Bryan Pagliano, a former Clinton aide who invoked his Fifth Amendment rights when called to testify before Congress, are worried that a proposed immunity deal could force Pagliano to give up his future right to decline questions.

Sens. Chuck Grassley and Ron Johnson pressed the Justice Department Monday on whether offering Pagliano a “proffer session” — a chance to outline what he knows without fear of legal consequences — would constitute an official waiver of his Fifth Amendment rights moving forward.