US ambassador to China resigns, presidential run expected

Ambassador Jon Huntsman, a Republican, sent his resignation letter to President Barack Obama late Monday, the Politico reported.

White House spokesman Robert Gibbs had said earlier in the day that Huntsman was expected to leave sometime in the first part of the year.

Huntsman was governor of Utah when he was tapped by Obama to serve as ambassador in 2009. Obama has lauded him for his stature in the region and his fluent Mandarin.

When asked during the recent visit of Chinese President Hu Jintao about rumours that Hunstman might want to challenge him in the 2012 presidential elections, Obama drew laughter from the press corps.

"I couldn't be happier with the ambassador's service. And I'm sure he will be very successful in whatever endeavours he chooses in the future," Obama joked.

"And I'm sure that him having worked so well with me will be a great asset in any Republican primary," he addded.