Updated, 6:20 p.m.

Petitions have failed. Lawsuits have failed. Even campaign pledges from future presidents have failed. So now one Guantanamo Bay detainee is hoping that Twitter can help him shut down the infamous detention facility.

Shaker Aamer, a Saudi citizen and former British resident, is one of 103 Guantanamo detainees currently on a hunger strike in protest of his seemingly endless incarceration without trial. Eleven years into his confinement, Aamer's interactions with the outside world are limited. But through his lawyers, Aamer is testing the ability of social media to pressure President Obama into finally closing Guantanamo.

Clive Stafford Smith, who runs the UK human-rights legal firm Reprieve, tweeted this morning that "Shaker Aamer would like everyone" to call the U.S. embassy in London "to demand action on Guantanamo Bay." He's got 80 retweets as of this writing.

Lawyers routinely take their cases into the court of public opinion to stir sympathy, and social media provides a new route for doing so. According to Stafford Smith, however, the idea for the tweets came from Aamer, whose detention on suspicion of being a member of al-Qaida predates the existence of Twitter by four years.

"He really does know about Twitter and all the social media," says Stafford Smith, "as I have sent him copies of what people have said and done for him to keep his spirits up."

The specific request came through the Reprieve lawyer working on Aamer's case, Cori Crider, who visited Aamer at Guantanamo at the beginning of the month. According to Crider's notes from a May 1 meeting, the air conditioning in Aamer's cell is kept at 70 degrees, "which is very cold for someone who has not eaten for 90 days," and a Guantanamo official referred to as "the Rover" informed Aamer that detainees who meet with their lawyers "must be searched thoroughly and including your private parts."

Of the 166 detainees still at Guantanamo, 103 are on a hunger strike, according to Army Lt. Col. Todd Breasseale, a Pentagon spokesman. Breasseale declined to comment on the Twitter campaign, but confirmed that 30 of the Guantanamo hunger strikers have been force-fed via an enteral feed. Stafford Smith said that Aamer is not one of them.

It's unclear how many people have called the London embassy on Aamer's behalf. The number Stafford Smith tweeted out reaches an automated switchboard, not a human being at the embassy. (The embassy says it's not sure how many calls it's received, but encourages anyone who wants to register a perspective on U.S. policy to do so through the "Your Views" section of the voicemail system accessible from the switchboard.) Shaheen Malik, who tweets as @sheenamal01, @-mentioned Stafford Smith: "got a lots of bullshit back, as to how Mr president has been trying to shut gitmo down, demcratically!!" Keith Brindle (@BrindleKeith) tweeted: "Think they are getting wise to what's happening. The embassy just cut me off. Such democratic souls."

The hunger strike has renewed pressure on Obama to close Guantanamo, an option that faces considerable opposition from a bipartisan phalanx in Congress. In March, the commander of U.S. forces in South America, Marine Gen. John Kelly, partially attributed the strike to a sense of detainee desperation over Obama's inability to close the facility. Obama plans to deliver a major national-security speech on Thursday, in which he reportedly will outline his new plan for belatedly fulfilling a major pledge from his first presidential campaign.

It's worth mentioning that Obama's plans thus far to close Guantanamo don't necessarily involve letting detainees go. An effort undertaken by a key congressional ally, Sen. Dianne Feinstein (D-Calif.), identified civilian and military prisons capable of housing the residual detainee population, thereby relocating and not ending the indefinite detention practices that caused Guantanamo to become a source of international outrage. Aamer's indirect tweeting might tie up the London embassy in phone calls – his detention is the source of transatlantic tension between the two close allies – but even the closure of Guantanamo doesn't translate to his freedom.

"I like the idea that Shaker, who the military thinks is lonely in his cell 100 days towards hunger strike starvation," Stafford Smith says, "is able to get a note to me through the censors that I can tweet to 12,000 people, who in turn send his message on to several millions."