The whistleblower-versus-traitor argument has taken on a new dimension with recent moves to curtail the programs that Mr. Snowden revealed. A federal judge ruled that one program was probably unconstitutional, technology companies are demanding changes, lawmakers are considering restrictions, and even a White House panel urged modifications.

If the programs are so debatable, advocates for Mr. Snowden argue, then he should not be punished for bringing them to light.

“I absolutely think the tide has changed for Snowden,” said Jesselyn Radack, a legal adviser to Mr. Snowden and a lawyer with the Government Accountability Project, an advocacy group. “All of these things taken together counsel in favor of some sort of amnesty or pardon.”