A dozen politicians and a half-dozen steelmakers teamed up to drive home the message to the U.S. International Trade Commission to level the playing field when it comes to trade with China.

They testified Tuesday before the ITC, where commissioners will determine whether the domestic steel industry was injured by alleged Chinese dumping of oil country tubular goods (OCTG).

Jay Williams, Mayor of Youngstown, Ohio, home to tubular manufacturer V&M Star Ohio, said the hearing was an opportunity for the federal government to send a strong message to domestic and international competitors.

"This is not about protectionism, it's about fairness," Williams said. "The U.S. market remains open for international business, but the United States will not allow foreign competitors to gain an unfair competitive advantage by way of trade policies which make it nearly impossible for domestic firms to compete."

The U.S. Commerce Department already issued determinations for a...