The future of a National Security Agency spying program that collects the phone records of millions of Americans hangs in the balance as Congress debates whether it should renew the section of a controversial surveillance law used to authorize it, allow that part of the law to expire or replace it with a compromise bill.

And the man who set off the current dialogue about government surveillance weighed in — on reddit.

Former government contractor Edward Snowden took to the link- and news-sharing site Thursday along with Jameel Jaffer, the deputy legal director of the American Civil Liberties Union, urging users to contact their legislators to oppose an extension of Section 215 of the USA Patriot Act.

Section 215 provides the current legal basis for the phone records program and is set to expire June 1 — although a memo from the Justice Department said the program would need to start shuttering this Friday if Congress did not act to renew the program.

Snowden did not directly address the USA Freedom Act, a compromise bill that has split some privacy advocates, except to argue that support for the bill from the White House and intelligence agency officials bolsters the case that the current phone program is "neither necessary nor valuable." The House has passed a version of the USA Freedom Act and is scheduled to be out of session until after Section 215 expires.

The ACLU neither supports nor opposes the bill, but has advocated for Congress to allow Section 215 to expire.  "The USA Freedom Act doesn’t go far enough," Jaffer said in a reddit post — although he called it at least "a step in the right direction, which is more than can be said for the straight reauthorization being proposed by the Republican leadership in the Senate."

Privacy advocates who support USA Freedom have argued that a straight expiration of Section 215 might leave the government free to restart the phone records program under some other authority.

One reddit user raised this point to Snowden. "Even if section 215 is not renewed, do you believe that the NSA/ US government will still accomplish phone surveillance without approval and in secret?" asked  user Tomcat1108.

"There are always reasons to be concerned that regardless of the laws passed, some agencies in government (FBI, NSA, CIA, and DEA, for example, have flouted laws in the past) will misconstrue the intent of Congress in passing limiting laws — or simply disregard them totally," Snowden said. "However, that's no excuse for the public or Congress to turn a blind eye to unlawful or immoral operations — and the kind of mass surveillance happening under Section 215 of the Patriot Act right now is very much unlawful."

A federal appeals court ruled this month that the phone program was illegal under the USA Patriot Act. The ACLU was the plaintiff in the case, but the appeals court declined to grant a preliminary injunction barring the NSA from collecting the group's call records,  citing the impending deadline and congressional debate over Section 215.

Supporters of the phone records program warn that letting Section 215 expire might harm national security interests. But a presidential review group and a majority of the Privacy and Civil Liberties Oversight Board have both released reports finding that the phone records program was ineffective.