Only hours after Chen Guangcheng left the embassy for a hospital checkup and reunion with his family, he began telling friends and foreign media they feel threatened and want to go abroad. At first taken aback at the reversal, the State Department said officials spoke twice by phone with Chen and met with his wife, with both affirming their desire to leave.

"They as a family have had a change of heart about whether they want to stay in China," department spokeswoman Victoria Nuland told reporters.

Nuland stopped short of saying whether Washington would try to reopen negotiations to get Chen abroad should Beijing agree. "We need to consult with them further to get a better sense of what they want to do and consider their options," Nuland said.

Chen’s still unresolved fate threatens to erode already shaky trust between Washington and Beijing at a time both governments are trying to contain their ever sharper jostling for influence around the world. His case hovered over Thursday’s opening of two-day talks on global political and economic hotspots led by Secretary of State Hillary Rodham Clinton, Treasury Secretary Timothy Geithner and their Chinese counterparts.

Chen remained in the hospital, its grounds ringed by a noticeable police presence, making it unclear how his exit could be arranged, and receiving medical tests.

A self-taught lawyer, Chen, 40, spent most of the last seven years in prison or under house arrest in what was seen as retribution by local authorities for his advocacy against forced abortions and other official misdeeds. His wife, daughter and mother were confined at home with him, enduring beatings, searches and other mistreatment.

His escape from house arrest to the fortress-like U.S. Embassy last week inserted Washington in the center of a human rights case, always a testy issue for Beijing, and at the same time potentially embarrassed Chinese leaders that the country is unable to protect its own citizens.

Chen’s goal, he told U.S. officials, was to secure the safety of his family and remain in China. Under painstaking arrangements negotiated over days, he was to be reunited with his family and relocated outside his home province to a university town where he could formally study law.

But later, in the hospital, Chen felt abandoned by the U.S., finding no embassy staff had stayed behind to assure his protection. His wife, Yuan Weijing — who is staying with him along with his daughter and a son who has been raised by relatives in recent years — began describing the rough interrogation she received once his escape became known and the fight his nephew got involved in when confronted by officials. Chen said he changed his mind, fearing for their safety if they remained in China.

"Yuan Weijing met him and told him what happened to his family, and that his family was tied to chairs and interrogated by police, and that his nephew attacked somebody and is on the run outside and might be in life-threatening dangers," said Li Jinsong, his lawyer. "These things undoubtedly have left an impact on him."

U.S. Ambassador Gary Locke defended the arrangements at a news conference Thursday and said "unequivocally" that Chen was never pressured to leave. Locke said Chen left the embassy after talking twice on the telephone with his wife, who was waiting at the hospital.

"It may not be everything that they would like or want, but this is a good proposal and we should take the first step," Locke said.

The alternative, Locke said, was a protracted negotiation, with Chen stuck in the embassy and his family at home and at risk.

"He knew that — and was very aware that he might have to spend many, many years in the embassy," Locke said.

It’s unclear whether China would be willing to negotiate further over Chen’s fate. The government already has expressed anger that the U.S. harbored a Chinese activist. Beijing sees as its right the authority to restrict the movements of Chinese citizens, and the Foreign Ministry reiterated its displeasure Thursday, calling the affair meddling in Chinese domestic matters.

The diplomatic dispute over Chen is sensitive for the Obama administration, which risks appearing soft on human rights during an election year or looking as though it rushed to resolve Chen’s case ahead of the strategic talks Clinton opened.

Clinton said in a speech that China must protect human rights, rejecting Beijing’s criticism of the U.S. for getting involved in Chen’s case.

Chinese President Hu Jintao told the gathering that China and the United States "must know how to respect each other" even if they disagree.

"Given our different national conditions, it is impossible for both China and the United States to see eye-to-eye on every issue," he said in the only part of the opening ceremony that was broadcast on state television. "We should properly manage the differences by improving mutual understanding so these differences will not undermine the larger interests of China-U.S. relations."

Should Beijing agree to negotiate, among the issues that would have to be worked out if Chen leaves China is whether he would go as a visiting scholar — an indication his stay would be temporary — and whether China would let him return. The government has at times revoked the passports of dissidents abroad, rendering them stateless.

A delay in figuring out how to help Chen may also undercut the U.S. bargaining power. Pressure for a resolution would subside once Clinton leaves China on Saturday.