Washington ? The Bush administration urged China on Wednesday to begin a transition to democracy, contending the existing one-party system “is simply not sustainable.”

The State Department’s No. 2 official also warned about possible economic action by Washington unless the U.S. trade deficit with Beijing shrinks.

In a single speech, Deputy Secretary of State Robert Zoellick assembled all elements – negative and positive – of the U.S.-China relationship. U.S. officials say it is the most complex of any in the world.

“Closed politics cannot be a permanent feature of Chinese society. It is simply not sustainable,” Zoellick said in a speech to the National Committee on United States-China Relations in New York.