Ms. Pelosi is hardly the only American politician taking China to task. On Friday, Senator John McCain, the presumptive Republican presidential nominee, traveling in France, warned that China’s behavior was “not acceptable” for a world power. Earlier in the week, Senators Hillary Rodham Clinton and Barack Obama, the two Democratic presidential contenders, issued strong criticisms of China.

Mr. Bush, too, has made a strong show of solidarity with the Dalai Lama. In October, he met privately with the Tibetan leader at the White House and then attended a ceremony at the Capitol, where the Dalai Lama was awarded the Congressional Gold Medal. It was the first time the two had appeared in public together, and the White House was well aware of the symbolism.

China analysts say the violence in Tibet demands that the president chart a careful course. “I think to the extent that he can work the issue privately, it’s better, frankly,” said Jeffrey A. Bader, an Asia specialist who worked at the National Security Council under President Clinton. “The public statements just make the Chinese dig in their heels all the more, make them more resolute in their repression.”

American presidents have historically found relations with China to be a delicate dance. But none more so than Mr. Bush, especially since September, when he met with China’s president, Hu Jintao, in Sydney, Australia, and accepted Mr. Hu’s invitation to attend the Beijing Olympics.

Mr. Bush has said that he wants to support American athletes and views the Games as a sporting event, but that he will use his attendance to put pressure on China to improve its human rights record. But human rights advocates have linked the Olympics with violence in the Darfur region of Sudan and have accused Mr. Bush of giving his imprimatur to a country that, in their view, is not exerting enough influence as a major buyer of Sudanese oil to stop what the White House has termed a genocide.

On Capitol Hill, two representatives, Dana Rohrabacher, Republican of California, and Neil Abercrombie, Democrat of Hawaii, are leading a push for a boycott of the Beijing Games. China analysts, though, say Mr. Bush has little choice but to attend, even if it means a political backlash at home.

“This is China’s coming out party,” said Michael Green, an Asia expert and former Bush administration official. “If he were to cancel, it would be such a loss of face for China that it would make working with them on issues from North Korea to human rights much more difficult.”