(CNN) -- Secretary of State Hillary Clinton is set to leave Monday night for China on a trip that is likely to be fraught with diplomatic tension over the status of escaped Chinese activist Chen Guangcheng, who is reportedly being sheltered at the U.S. Embassy.

Chen, a blind, self-taught lawyer, evaded guards who had kept him under house arrest for more than 18 months in a small eastern village and made his way to Beijing on April 22, friends and fellow activists said last week.

Once in the capital, Chen moved from one safe house to another before finding refuge at the U.S. Embassy, according to Hu Jia, a fellow activist and one of the few people who has said he has seen Chen since he arrived in Beijing.

The situation presents an extraordinary test for the Obama administration's approach to relations with China, creating a strain between upholding human rights and maintaining steady ties with Beijing.

Clinton and Treasury Secretary Timothy Geithner are scheduled to hold talks with Chinese officials in Beijing starting Thursday about strategic and economic issues. But the Chen affair could overshadow the economic talking points.

"If Chen is holed up in the U.S. Embassy, it is hard to fathom how the two sides will stay focused on the many pressing geostrategic and economic challenges in the relationship," Christopher Johnson, a China analyst at the Center for Strategic and International Studies in Washington, wrote in an opinion article for CNN.

The blind activist's flight from detention comes at a highly sensitive time for Chinese authorities. The ruling Communist Party has been rocked by a scandal involving the former high-ranking leader Bo Xilai, whose wife is under investigation in relation to the mysterious death of a British businessman in the southwestern metropolis of Chongqing.

The downfall of Bo, the former Chongqing party chief who is now being investigated in connection with serious disciplinary violations, has created shock waves ahead of a once-in-a-decade leadership transition in China that is due to unfold later this year.

American and Chinese officials have declined to comment directly on the Chen case. But John Brennan, one of President Barack Obama's national security advisers, said Sunday that the U.S. government is "working very closely with the individuals involved."

The United States is aiming to strike the "appropriate balance" between its commitment to human rights and its diplomatic relationship with China, Brennan said on Fox News.

The Republican presidential contender Mitt Romney said in a statement Sunday that he hopes the U.S. government will "take every measure to ensure that Chen and his family members are protected from further persecution."

Chen addressed Chinese premier Wen Jiabao in a video posted Friday on YouTube, detailing "cruel" abuses he said he and his family had suffered at the hands of authorities during months of heavily guarded detention in their home.

"They broke into my house and more than a dozen men assaulted my wife," he said. "They pinned her down and wrapped her in a comforter, beating and kicking her for hours. They also similarly violently assaulted me."

Journalists and supporters were prevented from visiting Chen during his house arrest. One of those supporters is Hollywood actor Christian Bale, who was roughed up by security guards while attempting a visit in December.

Chen, 40, rose to fame in the late 1990s thanks to his legal advocacy for what he called victims of abusive practices, such as alleged forced abortions, by China's family-planning officials.

A local court sentenced Chen to four years and three months in prison in 2006 on charges of damaging property and "organizing a mob to disturb traffic" in a protest, charges that his supporters called preposterous.

Since his September 2010 release from prison, he had been confined to his home along with his wife, mother and daughter.

Chen's escape appears to have angered local officials holding him captive, with supporters saying at least four members of his family have been detained.

In the YouTube video, the blind activist appealed to the Chinese premier to investigate his case and expressed concern about the welfare of his wife, mother and daughter.

"Although I'm free, my worries are only deepening," he said. "They have been persecuting my family for a long time, and my escape would only prompt them into a mode of revenge."

The authorities' reaction also seems to have ensnared Chen's supporters, especially those suspected of aiding his escape.

After speaking to CNN, Hu was taken away by police for questioning, his wife posted on Twitter.

Chen's friend He Peirong disappeared Friday, shortly after speaking to CNN and other news organizations about the blind activist's escape.

The last message she sent out, according to Bob Fu, head of the U.S.-based nonprofit group ChinaAid, was that state security agents had arrived at her home in the eastern city of Nanjing.

"I'm not concerned about my own safety," she told CNN. "I hope they'll arrest me, not my friends."

CNN's Steven Jiang and Jethro Mullen contributed to this report.

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