US President Barack Obama said Commerce Secretary Gary Locke will help strengthen relations with China as he announced his nomination as the new US ambassador to China on Wednesday.

Jon Huntsman, currently Washington's top diplomat in China, has decided to step down from his post on April 30 and is expected to make a run for the 2012 Republican presidential nomination.

Thanks to his Chinese ancestry and work to promote Sino-US trade, Locke, 61, beat other top candidates, including Jeff Bader, National Security Council senior director for Asian affairs, Bill Richardson, the former governor of New Mexico, and former US treasury secretary Henry Paulson, to become the US top diplomat to China.

"In replacing Ambassador Huntsman, I can think of nobody who is more qualified than Gary Locke," Obama said.

"More than 100 years ago, Gary's grandfather left China on a steamship bound for America, where he worked as a domestic servant in Washington state. A century later, his grandson will return to China as America's top diplomat," Obama said.

He praised Locke as "one of our nation's most respected and admired public servants" and recalled his achievement as the country's first Chinese-American governor in doubling Washington state's exports to China.

"As the grandson of a Chinese immigrant who went on to live the American Dream, Gary is the right person to continue this cooperation. I know he will bring the same skills and experience that he brought to commerce secretary to this new position that he's about to embark on," Obama said.

Locke said he was "deeply humbled and honored" to become the first Chinese-American ambassador to China.

Locke's grandfather went to the United States over a century ago to work as a houseboy for a family in Washington state in exchange for English lessons. His father was born in China and then moved to the US as a teenager.

"I'm going back to the birthplace of my grandfather, my father, my mom and her side of the family, and I'll be doing so as a devoted and passionate advocate for America, the country where I was born and raised," he said.

The White House nomination will now go to a Senate confirmation hearing.

Chinese Foreign Ministry spokeswoman Jiang Yu welcomed Locke's nomination as the new US ambassador to Beijing on Thursday, saying she hoped the new envoy could play a positive role in strengthening bilateral relations.

Locke was confirmed unanimously as commerce secretary by voice vote in 2009, but some analysts said that his confirmation this time will face some challenges as Congress will use the opportunity to press the administration on some China-related issues, such as the renminbi exchange rate.

Though most US trade organizations, companies and experts applauded Obama's pick and expected Locke to ease trade tensions with the world's second-largest economy, some worry that lack of experience with Congress may be his Achilles' heel.

"It is a great choice on the part of President Obama because the nomination of Gary Locke reflects the administration's emphasis on economic issues in bilateral relations and reaffirms the American values of inclusiveness and openness," Cheng Li, senior fellow at the Brookings Institution's John L. Thornton China Center, told China Daily.

"The potential weakness is that Locke does not have much experience in terms of working with the US Congress. As for the challenges, US-China relations go far beyond the domain of economics and trade."

Chi Wang, the president of the US-China Policy Foundation, said: "Every Chinese-American will feel very happy with this news.

"But it is not easy to ease the tension between the two countries. Locke may be good at trade, but he is not familiar with security issues."

US-China Business Council (USCBC) Chair Muhtar Kent said Locke's leadership roles in business and government, combined with his recent success in strengthening US-China commercial relations, make him ideally suited to be a strong and effective ambassador to Beijing.

"Over the long run, innovation, economic growth and diplomatic harmony are most effectively achieved by free and fair trade and open dialogue," said Kent, also chairman and CEO of The Coca-Cola Company.

USCBC President John Frisbie said as a former elected official, Gary Locke understands how the US public views the relationship with China.

"With his background as secretary of commerce, he understands that trade and investment ties with China are important to American jobs and economic prosperity," Frisbie said.