A crowd gathered in front of the U.S. Capitol on Thursday as members of Congress and witnesses to the events of June 4, 1989, criticized China for not coming to terms with its decision to send tanks and troops to crush demonstrations and shoot protesters seeking to remake the authoritarian Chinese system.

All this week, Washington has seen daily activities related to Tiananmen, including congressional hearings, appearances by the "Three Heroes of Tiananmen" and other activists, photo exhibits and candlelight vigils.

The leader of the House of Representatives, Democrat Nancy Pelosi, told the crowd at the Capitol that U.S. lawmakers would continue to urge China to match its economic success with political changes and allow more openness and freedom.

"If we do not support human rights in China and Tibet, we lose all moral authority to speak about human rights any place in the world," said Pelosi, who met last month with Chinese President Hu Jintao and Premier Wen Jiabao.

As the United States works to secure cooperation from a powerful, economically dynamic China, it has become difficult for activists and lawmakers to draw attention to Tiananmen and to claims that China abuses its citizens' rights.

Harry Wu, who spent 19 years in China's "laogai" labor camp system, said the reason that events on Tiananmen are overshadowed is clear: "Because China is holding so much bonds. Because China became a major producer of the United States."

China holds an estimated $1 trillion in U.S. government debt.

T. Kumar of Amnesty International said what is needed is "more powerful statements coming from the White House and the State Department to hold people accountable."

Secretary of State Hillary Rodham Clinton angered activists in February by saying during a trip to Beijing that the United States would not let its objections to China's human rights record interfere with cooperation with Beijing on global crises.

Clinton said in a statement Wednesday that China "should examine openly the darker events of its past and provide a public accounting of those killed, detained or missing, both to learn and to heal."

Beijing never has allowed an independent investigation into the military's crushing of the 1989 protests, in which hundreds abd possibly thousands of students, activists and ordinary citizens were killed.

Republican Rep. Chris Smith said the United States should put the well-being of China's citizens at the top of the countries' agenda. "That should be our priority," he said. "After that comes the trade and the economic issues."