WASHINGTON — Former Utah governor Jon Huntsman, after not quite two years as US President Barack Obama's ambassador to China, has returned home to weigh whether to seek the White House for himself in 2012.

But analysts warn that the 51-year-old former diplomat will likely struggle to win over fellow Republicans, notably the right-wing "Tea Party" movement built on anger at Obama and therefore suspicious of Huntsman's conservative credentials.

"It's an uphill battle," said Matt Dickinson, a political science professor at elite Middlebury College in Vermont.

Dickinson said Huntsman's service as the top US diplomat in Beijing -- a critical diplomatic post held by at least one future president, George Bush -- would be a "big handicap" in primaries dominated by core Republican voters.

Huntsman may say "I held my nose, I did it for the good of the country, particularly because so much our economic well-being is tied up in our relationship with China," the professor said.

"Some people will buy it, I suspect a lot of people will not," he said.

Obama has repeatedly spotlighted their relationship, vowing recently "to make sure that every primary voter knows it" and joking at Huntsman's expense during Chinese President Hu Jintao's visit to Washington in January.

"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 quipped.

Huntsman, whose resignation is effective Saturday, is expected to decide in the next two months whether to run, but already a group of political operatives in Washington, many of them veterans of Republican John McCain's White House bids, has done some of the organizational spadework to facilitate one.

They have started a political action committee -- HORIZON PAC, with the motto "Maybe Someday" -- that will cultivate local politicians and is expected ultimately to provide a campaign framework should Huntsman decide to run.

Huntsman plans to give a university graduation speech on May 21 in New Hampshire, which traditionally holds the first presidential primary, and will likely also hold low-key but campaign-style events, a supporter said.

"They will be a chance for him to meet some New Hampshire people, and for New Hampshire people to meet him," said Peter Spaulding, who chaired McCain's campaign in the state in the 2000 and 2008 White House contests.

"I think that he's a fresh, new, conservative Republican face in the race," Spaulding told AFP by telephone, before dismissing the notion that Huntsman's ambassadorship could hurt him.

"I don't think that's a major problem," said Spaulding. "In these types of non-partisan posts, you're serving the country, regardless of your political leanings."

Huntsman is well regarded in China, due to his fluent Mandarin and the fact that one of his seven children is a girl adopted from China. He is also known for preferring his bicycle to chauffeur-driven armored vehicles.

He has helped Washington navigate a particularly thorny time in relations between the world's top two economies, during which they have battled over everything from the yuan and trade to Taiwan and Internet freedom.

Among Republican voters, however, he is not well known.

A mid-April poll by the respected Gallup organization found that just 21 percent of them knew his name -- against 82 percent for possible rival and former Massachusetts governor Mitt Romney.

University of Utah political science professor Matthew Burbank told AFP that "the problem that Huntsman has this time around" is that Romney, who like Huntsman is a Mormon, is a "more established" candidate with a similar profile.

When it comes to Mormon fundraisers and organizers, "Romney's pretty well got them lined up," depriving Huntsman of potentially important backers, Burbank told AFP.

In Utah, Huntsman cruised to election and then reelection as governor and won strong reviews for his careful husbanding of the state's finances.

"He proved himself to be a very capable governor," said Burbank.

But he also praised Obama's economic stimulus package backed civil unions for gay couples, and supported a "cap-and-trade" plan to curb greenhouse gases blamed for global warming -- all targets of Republican scorn.

And some commentators say his Mormon faith could irk evangelical Christian voters who comprise a key part of the Republican party base vote.

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