The administration’s handling of a Chinese dissident seeking protection from his government emerged Thursday as a political vulnerability for President Obama at a time when he has made his record on foreign affairs a prime argument in his reelection bid.

As Chen Guangcheng continued to seek U.S. help, even calling in to a congressional hearing from a Beijing hospital, his case entered the campaign bloodstream with the presumptive Republican presidential nominee, Mitt Romney, calling the fast-moving events “a dark day for freedom.”

“And it’s a day of shame for the Obama administration,” Romney said at a campaign event in Portsmouth, Va. “We are a place of freedom, here and around the world, and we should stand up and defend freedom whenever it is under attack.”

Chen’s uncertain fate drew sharp questions Thursday in Washington about the administration’s management of his case, bringing to a close the Obama campaign’s days-long effort to highlight the president’s foreign policy expertise on the first anniversary of the U.S. raid that killed Osama bin Laden.

In recent months, Romney has accused Obama of not standing up to authoritarian governments., including those of Syria, Russia and Iran

He suggested Thursday that the Chen case proved his point, saying American officials may have “sped up” Chen’s departure from the U.S. Embassy, where he had gone after escaping house arrest, to preserve the talks that Secretary of State Hillary Rodham Clinton and Treasury Secretary Timothy F. Geithner are holding in Beijing.

At the White House, press secretary Jay Carney directed most questions about Chen’s case to the State Department, saying it is a diplomatic matter. He said Obama is receiving updates but declined to give a “play by play” of what he is doing to resolve the issue.

“I can assure you that the president is not concerned about political back and forth on this issue,” Carney told reporters.

“He is focused on the need to advance U.S. interests in our broad-based relationship with China — very important economic, diplomatic relationship with China,” Carney continued. “He has and will continue to make it a priority in that relationship, or part of that relationship, an open and frank discussion of our concerns about human rights.”

Later in the day, Chen called in to the congressional hearing on his case, at which House Republicans raised concerns about the administration’s handling of it.

Rep. Christopher H. Smith (R-N.J.), who heads the Congressional-Executive Commission on China , quoted Chen as saying that he was “very disappointed” in U.S. officials and added that he would seek to find out during a hearing next week whether their approach to the talks was affected by a desire not to let Chen’s case disrupt Geithner and Clinton’s visit.

Smith said the administration must answer a number of questions, including how any agreement to keep Chen and his family safe in China might be enforced; how the United States would respond if Beijing experienced retaliation; and the fate of Chen’s nephew, Chen Kegui, who was reportedly taken into custody after his uncle’s escape.

Rep. Frank R. Wolf (R-Va.) said White House officials have questions to answer.

“The most generous read of the administration’s handling of the situation was that it was naive,” he said, adding that he plans to review all the cable communications — classified and not — pertaining to the Chen deal.

“The Obama administration has a high moral obligation to protect Chen and his family,” Wolf continued. “To do anything less would be scandalous.”