Nefeterius A. McPherson, a spokeswoman for the Office of the United States Trade Representative, said that the office had accepted the union’s petition and would reach a decision on whether to open an investigation of Chinese trade practices within the designated 45 days, even though the administration has the option of extending that deadline.

The filing of the trade case comes as trade and currency frictions with China are mounting. On Friday morning in Beijing (late Thursday night in New York), China announced that it ran another large trade surplus in August of $20.03 billion.

The Chinese mission to the W.T.O. in Geneva declined to comment on the steelworkers’ filing on Thursday, on the grounds that no case had been filed yet at the W.T.O. and that any initial consultations between the United States and China would be bilateral.

Wang Baodong, a spokesman for the Chinese Embassy in Washington, urged cooperation instead of confrontation: “Great potential exists between China and the U.S. in developing clean energy. And both the Chinese and the U.S. governments support their enterprises in collaborating in this promising sector, with the aim of creating a win-win situation commercially and helping combat the climate change effect.”

The issues go beyond jobs and exports, having real implications for efforts to curb global warming. Increasing China’s use of renewable energy for its own electricity needs would help slow the rise in China’s emissions of greenhouse gases. China passed the United States in total emissions in 2006, although emissions per person remain three times as high in the United States as in China.

Chinese energy policy makers have said in the past that developing a strong energy industry is a national priority that contributes to Chinese energy security. They say that China is helping to address global warming by rapidly increasing its output of renewable energy equipment and that the rest of the world should appreciate its heavy investment in clean energy, which has steeply pushed down the price of solar and wind energy in the past three years.