As United States Trade Representative, Portman attended the WTO's Hong Kong conference in 2005. He addressed the conference with a speech on development in Doha, and advocated a 60% cut in targeted worldwide agricultural subsidies by 2010. Portman then sponsored a claim against China for extra charges it levied on American auto parts. U.S. steel manufacturers subsequently beseeched the White House to halt an influx of Chinese steel pipe used to make plumbing and fence materials. This was a recurring complaint and the United States International Trade Commission recommended imposing import quotas, noting "the economic threat to the domestic pipe industry from the Chinese surge." With Portman as his top trade advisor, Bush replied that quotas were in the U.S. economic interest. He reasoned the American homebuilding industry used the pipe and wanted to maintain a cheap supply and that other cheap exporters would step in to fill China's void if Chinese exports were curtailed. This occurred at a time when the U.S. steel industry lost $150 million in profit between 2005 and 2007, although China's minister of commerce cited the U.S. industry's "record high profit margins" in the first half of 2004 and continued growth in 2005. China next lobbied Portman to leave matters alone, meeting with his office twice and threatening in a letter that restrictions and what it called "discrimination against Chinese products" would bring "serious adverse impact" to the U.S.-China economic and trade relationship. Portman vowed to "hold [China's] feet to the fire" and provide a "top-to-bottom review" of the U.S.–China trade relationship. His claim that China had improperly favored domestic auto parts became the first successful trade suit against China in the WTO. During Portman's tenure as trade ambassador, the U.S. trade deficit with China increased by 21 percent.