Rep. Rob Portman (search) won Senate Finance Committee endorsement Tuesday to become the next U.S. trade representative, but his confirmation by the full Senate still faced a roadblock put up by a single senator.

The committee voted without dissent for the Ohio Republican, who as trade representative would be responsible for negotiating new free trade agreements, resolving trade disputes with China and other countries and coordinating U.S. policy with the World Trade Organization (search) and other international groups.

Portman was nominated by Bush last month to succeed Robert Zoellick (search), who has moved in Bush's second term to the No. 2 post at the State Department.

While Portman is expected to be easily confirmed when the full Senate votes, that vote is being held up by Sen. Evan Bayh, D-Ind., who is exercising the right of any single senator to block a confirmation vote to protest U.S. policies toward countries such as China that subsidize export industries.

Bayh wants assurances from the Senate's Republican leaders that he will get a vote on a bill to make it easier to pursue unfair trade cases against China in the area of government subsidies.

Portman, in confirmation hearings before the Finance Committee earlier this week, said the United States needs a tougher approach toward China, which last year had a $162 billion trade surplus with this country.