Top Beijing posting may go to Chinese-American

If the posting is confirmed by the Senate, Mr Locke would be the first Chinese-American to hold the sensitive job.

He would succeed Republican Jon Huntsman, the former Utah governor, who is seen as a potential challenger to Mr Obama in the 2012 presidential race.

"As one of the world's fastest-growing economies, our relationship with China is one of the most critical of the 21st century. Over the last two years, we've worked hard to build a relationship that serves our national interests," Mr Obama said at the White House with Mr Locke at his side.

"As the grandson of a Chinese immigrant who went on to live the American dream, Gary is the right person to continue this co-operation," Mr Obama said. "I know he will bring the same skills and experience that he brought to commerce secretary to this new position."

The ambassadorship to China is one of the most critical jobs in US diplomacy, given America's complex and sometimes strained ties with the huge and growing Asian power.

Mr Locke, 61, said it would have been one of late father's proudest moments "to see his son named as the United States' ambassador to his ancestral homeland".