Concern is mounting about China's plan to prosecute democracy campaigner Liu Xiaobo on Wednesday on charges of inciting state subversion.
U.S. Senator Patrick Leahy told Congress this week that Liu's prosecution requires a serious response from the United States.
He said Washington wants to expand its cooperation with Beijing. But he said the persecution of Chinese citizens exercising universally recognized human rights hinders that cooperation and China's own development.
Liu has been in detention for more than a year for his role in writing "Charter 08," a pro-democracy manifesto calling for human rights and political reform of China's one-party system. The petition attracted 300 signatures and many more supporters on the Internet.
The European Union and United States have called on China to release Liu, while rights groups say the case ignores Beijing's universal human rights commitments and should be dropped.
Sophie Richardson of Human Rights Watch says the only purpose of the trial is, in her words, "to dress up naked political repression in the trappings of legal proceedings."
Senator Leahy said if the case moves forward, top officials from the U.S. Embassy and former U.S. Attorney General Richard Thornburgh should observe the trial.
Liu faces 15 years in prison if convicted. The former university professor has been in prison before. He spent nearly two years in detention after the 1989 crackdown on pro-democracy protesters in Beijing's Tiananmen Square.