Utah Governor Jon Huntsman speaks next to U.S. President Barack Obama after accepting the nomination to be the new United States Ambassador to China, at the White House in Washington in this May 16, 2009 file photo.

WASHINGTON / BEIJING - US Ambassador to China Jon Huntsman resigned on Monday, amid reports that he might seek the Republican nomination in 2012 and try to deprive President Barack Obama of a second term.

Huntsman, a former Utah governor, handed his resignation letter to the White House and the resignation will be effective from April 30.

White House spokesman Robert Gibbs sidestepped questions about Huntsman's political intentions, as anticipation builds for Obama's re-election bid and several prominent Republicans take soundings of their chances.

"I have talked to several people in the building, I have not heard anybody say that they know what the future holds for Ambassador Huntsman," Gibbs said.

Obama's 2009 choice of Huntsman to serve in the crucial Beijing post was seen as a political masterstroke, potentially taking one possible rival out of the game in the upcoming presidential election.

But Huntsman stirred 2012 speculation with a Newsweek interview late last year in which he suggested he had one political run left in him. He said this after buying a new home in Washington.

Huntsman, the son of a chemical billionaire, could inject his own cash into an effort to explore his prospects in the field of presumed Republican contenders for the presidential nomination.

He would bring solid foreign policy and economic credentials to the table, after two years steering perhaps the most important, and often troubled, US diplomatic relationship.

But many commentators believe his service as a member of Obama's government will prove a huge liability in wooing the conservative voters who dominate the Republican Party nominating process. And some of his more centrist positions on issues like climate change and immigration may also prove problematic in the Republican primary. Other commentators say his Mormon faith could irk evangelical Christian voters who comprise a key part of the Republican party base vote.

Obama made a reference to Huntsman's prospects when he was asked about his envoy's political intentions during a White House press conference with Chinese President Hu Jintao in January.

He said Huntsman had done an "outstanding job" and shown enormous skill, dedication and talent.

"I'm sure he will be very successful in whatever endeavors he chooses in the future, and I'm sure that him having worked so well with me will be a great asset in any Republican primary," Obama added.

China said on Tuesday that Ambassador Huntsman had helped boost Sino-US ties during his brief stint in Beijing.

"China acknowledges the contributions made by Ambassador Huntsman to promote active cooperation and the development of comprehensive relations between China and the US," Chinese foreign ministry spokesman Hong Lei said.

Whichever post he may pursue, Huntsman's expertise in Chinese affairs would certainly bring more understanding between the two nations, yet national and party interests take prominence in driving China policy in the United States, said Chinese analysts.

Huntsman was well regarded in China, partly due to his fluent Mandarin and his adopted Chinese daughter. He is also known for preferring his bicycle to chauffeur-driven armored vehicles.

His experience as a former deputy US trade representative overseeing Asia was also frequently mentioned in Beijing, as was his time as US ambassador to Singapore.

Agence France-Presse