(CNN) -- The presidential candidates are calling on China to improve its human rights record as protests over the crackdown in Tibet follow the Olympic flame on its international journey.
Sen. Hillary Clinton says President Bush should not attend the Olympic opening ceremonies.
All of the presidential candidates have condemned China for the way it has handled demonstrators calling for democratic freedoms and self-rule in Tibet and neighboring Chinese provinces.
Sens. Barack Obama and John McCain both advocate a tougher approach toward the Chinese government, but Sen. Hillary Clinton is the first of the candidates to suggest President Bush skip the Olympic opening ceremonies in Beijing.
The New York senator on Monday called on the president to boycott the ceremonies, citing recent protests in Tibet and the Chinese government's failure to pressure the government of Sudan to end the violence in Darfur.
"I believe President Bush should not plan on attending the opening ceremonies in Beijing, absent major changes by the Chinese government," she said in a statement.
Clinton has not asked the athletes to skip the events.
Fifteen U.S. House members earlier this month asked Bush not to attend the Olympic Games at all, and House Speaker Nancy Pelosi separately called for Bush to consider a boycott of the opening ceremony.
Bush has said he intends to meet with China's president during a trip to see the Beijing Olympics, which begin August 8.
Obama, Clinton's rival for the Democratic nomination, has said he is torn in his views on the issue.
"I'm of two minds about this," the Illinois senator said in a CBS interview last week.
"On the one hand, I think that what's happened in Tibet; [and] China's support of the Sudanese government in Darfur, is a real problem." But, he added: "I'm hesitant to make the Olympics a site of political protest because I think it's partly about bringing the world together."
In a statement Monday, the Illinois senator said is "deeply disturbed" by the recent events in Tibet.
"As I have said repeatedly, the Chinese government must take immediate steps to respect the dignity, security, human rights and religious freedom of the Tibetan people, to provide foreign press and diplomats with access to the region, and to finally work with the Dalai Lama toward meaningful autonomy for Tibet. If they do not, there should be consequences," he said.
"China could bolster its claim that it is peacefully rising by being more transparent about its significant military buildup, by working with the world to isolate pariah states such as Burma, Sudan and Zimbabwe, and by ceasing its efforts to establish regional forums and economic arrangements designed to exclude America from Asia," he said in a speech to the Los Angeles World Affairs Council.
"Until China moves toward political liberalization, our relationship will be based on periodically shared interests rather than the bedrock of shared values," said McCain, the presumptive Republican presidential nominee.
U.S. and other Western leaders have called on China to provide civil rights and freedoms to those in Tibet and to enter peaceful discussions aimed at resolving the crisis. Chinese authorities have accused the Dalai Lama of instigating violence in Tibet -- an allegation he rejects.
The International Olympic Committee has spoken strongly against any call for a boycott of the Games, though its position on world leaders skipping the opening ceremony is less clear.
IOC President Jacques Rogge said last month that a boycott of the Olympics "doesn't solve anything."
The Olympic flame, traveling across five continents, has been met with widespread demonstrations from people protesting China's human rights record.
The Olympic flame arrived in San Francisco, California, early Tuesday. California is the only U.S. stop for the flame, wrapping up the first week of a 23-city international tour. The flame will then return to China in May for a relay through the host nation. E-mail to a friend
CNN's Kristi Keck and Rebecca Sinderbrand contributed to this report.