U.S. union workers expressed confidence on Wednesday that President Barack Obama would restrict tire imports from China, as a 15-day countdown began for Obama to make his decision in the closely watched case.

"President Obama will have the opportunity to let American workers know he will stand with them when trade distorting practices from China threaten American jobs and our industries," Leo Gerard, president of the United Steelworkers Union said in a statement.

"We are confident the president shares our values of promoting a rising standard of living for the American worker. This trade case gives him the chance to put into practice his pledge to level the playing field and give all Americans a chance to share in the benefits of balanced trade," he said.

The Steelworkers endorsed Obama during last year's presidential campaign, helping him win a hard-fought race with rival Hillary Clinton for the Democratic party's nomination.

Both opponents and supporters of restrictions have called the case a key test of Obama's approach to trade in the face of conflicting pressures to protect jobs and promote free trade.

The U.S. Trade Representative was due to give Obama its recommendations in the tires case on Wednesday. That begins the final stage of deliberation in which Obama is required under U.S. trade law to announce a decision within 15 days.

U.S. tire imports from China totaled about 46 million in 2008, or triple the 15 million in 2004.

The White House will have no comment on case until Obama announces his decision, a White House spokesman said.

Opponents of the relief said U.S. tire manufacturers like Bridgestone/Firestone, Goodyear , and Cooper made a decision years ago to get out of the low end tire market that China supplies and have no intention of returning to it.