Obama said he knew Huntsman's nomination "wouldn't be the easiest decision to explain to some members of his party." But Obama said Huntsman was "the kind of leader who always puts country ahead of party and is always willing to sacrifice on behalf of our nation."
Elected to his second term in November, Huntsman said he wasn't looking for a new job and didn't expect "to be called into action" by McCain's winning rival.
"But I grew up understanding that the most basic responsibility one has is service to country," he said, standing with Obama as his family looked on. "When the president of the United States asks you to step up and serve in a capacity like this, that to me is the end of the conversation and the beginning of the obligation to rise to the challenge."
Huntsman will be 56 in 2016, young enough to handle the rigors of a national political campaign. Republican strategists say serving as U.S. envoy to China -- which Obama says will be critical to solving many world problems -- will only improve Huntsman's reputation.
LaVarr Webb, a Republican strategist in Utah, said the appointment is a plus for Huntsman. He said Huntsman became a long shot for 2012 after his headline-making call for the GOP to moderate its tone if it wants to rebound from 2008 election losses.
"Clearly Gov. Huntsman does have major political ambitions and serving as ambassador to China certainly gives him foreign policy credentials," Mr. Webb said.
Eric Hyer, a China expert and political scientist at Brigham Young University, said the decision surprised him because no one seeks the presidency from an ambassador's post.
"So he might serve for four years and then come back and run for president. But can you run against the guy who hired you?" Mr. Hyer said.