An online effort to save an alleged whistleblower is blowing up. Thousands of journalists, press advocates and free-speech supporters are urging the U.S. Department of Justice to abandon its prosecution of Jeffrey Alexander Sterling, the former CIA officer accused of leaking classified information about the government’s embarrassingly ill-conceived effort to sabotage Iran’s nuclear program.

That effort, dubbed Operation Merlin, was famously detailed in a 2006 book by James Risen, who has steadfastly refused to reveal his sources, even in the face of multiple government subpoenas. Despite Risen’s silence, Sterling, who worked for the CIA for almost a decade, was charged with the leak in 2011, following a lengthy government investigation. His trial is set for next month.

On Monday, the group launched a petition calling for Sterling’s release. The group says blowing the whistle on reckless government activities is not a crime but a “public service,” and supporters apparently agree. Within 24 hours, the petition had attracted more than 15,000 signatures, according to Norman Solomon, a coordinator for the group. By Tuesday afternoon, almost 20,000 people had signed on to the cause.

Sterling was indicted under the Espionage Act of 1917, but RootsAction said the charges against him reek of “selective prosecution.” The petition notes that other accused leakers (for example, General James Cartwright, who was targeted in a 2013 leak investigation related to the Stuxnet virus) did not face prosecution. Writing for the Nation in October, Solomon and co-author Marcy Wheeler characterized the charges as an undemocratic “vendetta.”

A federal judge on Tuesday ordered Risen to appear in court next month, but DOJ prosecutors reportedly say they will not ask him to reveal the source of the leak.   

As International Business Times reported on Monday in relation to the ongoing hacking scandal at Sony Pictures Entertainment, the First Amendment generally protects journalists and news organizations from reporting on information, even if it’s illegally obtained. Laws protecting government whistleblowers are somewhat more ambiguous and have been hotly debated since Edward Snowden uncovered the government’s mass surveillance tactics last year.

The Obama administration, meanwhile, has been heavily criticized for its frequent use of the Espionage Act as a way of cracking down on government workers who leak information to the press.

RootsAction’s petition, addressed to Obama and U.S. Attorney General Eric Holder, has a goal of 25,000 signatures. At the rate it’s growing, it’s likely to reach that goal by the end of the day.

Christopher Zara is a senior writer who covers media and culture. Got a news tip? Email me here. Follow me on Twitter @christopherzara.