A liberal senator is keeping left of Hillary Clinton during Congress' debate over the National Security Agency's surveillance programs, but it's not Elizabeth Warren, the progressive hero and favorite of many in the movement to oppose Clinton in the primary.
Instead, as Congress considers pulling back the Patriot Act's spy programs, it's Vermont independent Bernie Sanders—the Senate progressive who's actually running for president—who's mounting a challenge.
Only Sanders has staked out a strong enough position to conceivably put pressure on Clinton. Warren has recently kept quiet about the programs, and Martin O'Malley, the former governor of Maryland who is likely to enter the Democratic race later this month, has even less to say on the topic.
Sanders' opposition to the NSA's spying programs is clear—he's called them "Orwellian" and invasive—but he hasn't said whether he'll vote for the version of the USA Freedom Act that has been put forward in this session of the Senate.
Sanders also has a history of progressive votes on the issue. He emphasized in a Time op-ed published last week that he's never voted for the Patriot Act, which authorized the NSA's bulk-surveillance programs after the 9/11 terrorist attacks. Last November, he voted for the USA Freedom Act, which would have ended the NSA's bulk-data gathering.