The flight of Chen Guangcheng, a campaigner for disabled rights and against coercive family planning, is a challenge for China’s authoritarian government and, if it’s confirmed he is in U.S. custody, for Washington too. Assistant Secretary of State Kurt Campbell began a hurried mission to Beijing on Sunday to smooth the way for annual talks involving his boss, Hillary Clinton, Treasury Secretary Timothy Geithner and scores of officials.

Though Chen — a self-taught legal activist described by friends and supporters as calm and charismatic — hardly seems a threat, security forces and officials have reacted angrily, detaining several of his supporters and a nephew who fought with officials after the escape was discovered is on the run.

Police showed up at the home of veteran activists Zeng Jinyan and Hu Jia, who met with Chen last week while he was hiding in Beijing. Police took Hu away Saturday for 24 hours. They questioned Zeng for about a half-hour at home, sounding, she said, "very unhappy" about Chen’s flight.

"They were really irritated," Zeng said. "It was a big shock for them."

Ai Xiaoming, a documentary film maker based in southern Guangzhou city, said Chen’s escape has had the biggest emotional impact on Chinese rights advocates since jailed dissident Liu Xiaobo won the Nobel Peace Prize two years ago.

"There are many people now drinking toasts to him for the way he broke through his captivity, his difficulties, and pursued freedom," said Ai. "It’s what we all want for ourselves in our hearts. Chen Guangcheng is an example to us. If a blind person can break out of the darkness to freedom, then everyone can."

China’s state-controlled media have so far ignored the story despite its gripping narrative and the serious implications it could have on Sino-U.S. relations. Anything vaguely related to Chen has been blocked on Chinese social media sites, such as posts including or key word searches for Chen, Guangcheng, GC, or even the words "blind person."

The media blackout and online controls haven’t prevented China’s Internet savvy activist community from learning about or celebrating Chen’s escape. After state television aired a rerun Saturday of the American prison break film "Shawshank Redemption," some gleefully tweeted that it was an indirect nod to Chen. "Shawshank Redemption" became a banned search term.

Chen’s whereabouts have yet to be confirmed. Activists in China and overseas have said Chen is either under U.S. protection or in the U.S. Embassy.

Chen’s escape comes as the Chinese leadership is already reeling, trying to heal divisions over the ousting of a powerful politician, Bo Xilai, and complete a once-a-decade transition to a new generation of leaders. As in Chen’s case, the U.S. is implicated: Bo’s ouster was precipitated by the sudden flight of an aide to the U.S. Consulate in Chengdu.

While the aide, Wang Lijun, gave himself up to Chinese authorities — and though Republicans have criticized President Barack Obama for letting a valuable intelligence asset go — the incident and Chen’s escape reaffirm long-held suspicions by Beijing that the U.S. wants to undermine the communist government. Late last week, the White House, in a reversal, said it was considering selling new warplanes to Taiwan — the democratic island China claims as a breakaway territory.

It’s not known what Chen’s intentions are: some say he wants to stay in China. But negotiating any exit from U.S. custody is likely to be difficult for the Obama administration. Beijing is likely to be wary of any concessions, fearing they might embolden other activists.

Without confirming if Chen is in U.S. hands, Obama’s counterterrorism adviser John Brennan said the president would work to further human rights while preserving ties with Beijing.

"I think in all instances the president tries to balance our commitment to human rights, making sure that the people throughout the world have the ability to express themselves freely and openly, but also that we can continue to carry out our relationships with key countries overseas," Brennan said on the U.S. television news show "Fox News Sunday".

Complicating any negotiations over Chen is the treatment of his family. While Chen escaped a week ago from Dongshigu village and made it 600 kilometers (370 miles) northwest to Beijing, his wife and 6-year-old daughter were left behind. The whereabouts of several other relatives, including Chen’s mother and brother, are unknown.

Seven lawyers have volunteered to defend Chen’s nephew, Chen Kegui, who allegedly confronted and stabbed local officials who stormed his house in the middle of the night on Thursday in apparent retribution for the activist’s escape.

One volunteer lawyer, Liu Weiguo, said he spoke with Kegui briefly Sunday afternoon via mobile phone. Kegui told the lawyer he was by a highway about 120 kilometers (75 miles) from his home village, penniless and hoping to find a local police station where he could turn himself in.

"Since he escaped, they haven’t punished his persecutors in Shandong" province, said Zeng, the Beijing activist. "Instead it’s the activists and supporters who have been detained or disappeared. It’s very clear that Chen’s supporters and family members are very vulnerable right now."

Among the activists still in custody are He Peirong, a Nanjing activist and Chen supporter who drove the blind lawyer’s getaway car out of his home province of Shandong, and Guo Yushan, a Beijing scholar and rights advocate who aided Chen in the capital.

For a rural activist, Chen had gathered a wide following, a testament to what supporters describe as his generous spirit and determination to fight injustice. His exposure of forced abortions and sterilizations in his community so angered officials, they persecuted him, sending him to jail for four years and then upon his release confining him to his home, where he was isolated and occasionally beaten.

Civil rights lawyers, journalists, diplomats and even British actor Christian Bale have tried to penetrate the heavy security that has surrounded Chen for the last 20 months. Each time, hired guards drove them back, sometimes pelting outsiders with rocks and chasing them with cars.

For China’s human rights defenders, Chen’s dash to freedom was a bright spot after nearly two years of mounting harassment. Ai, the documentary filmmaker, said Chen’s hardships have been unique but his aspirations for a more open society with greater legal protections are shared by many.

"We have jails inside ourselves that make us worry that we will be punished if we speak our minds because this society doesn’t respect the rule of law and doesn’t fully protect freedom of speech," she said. "Chen Guangcheng is a model, and he has shown us that we can break away from those fears."