Amnesty International, Human Rights Watch and the US group ACLU launched a campaign Wednesday to push President Barack Obama to pardon Edward Snowden, the fugitive NSA whistle-blower living in Russia.

The campaign’s main prod is an online petition urging Obama to give Snowden amnesty before his term ends in January.

The petition, at pardonsnowden.org, has already been signed by high-profile lawyers and celebrities including writer Joyce Carol Oates and actor Martin Sheen.

The chances of a pardon appear slim for Snowden, a former contractor for the National Security Agency who released thousands of classified documents in 2013 revealing the vast US surveillance put in place after the September 11 attacks.

The US authorities charged Snowden with espionage and theft of state secrets after he gave the documents to journalists Glenn Greenwald, Laura Poitras and Ewen MacAskill. He faces up to 30 years in prison.

Considered a traitor by some and a hero by others, the 33-year-old fled to Hong Kong, where he hid among Sri Lankan refugees in cramped tenements, and later received political asylum in Russia after the United States revoked his passport while he was en route to Ecuador.