A week after leaving his post as U.S. ambassador to China, Jon Huntsman appeared to edge closer to challenging his former boss for the White House, meeting with top Republican Party leaders here and telling an audience of graduates that America is “still the envy of the world, we are still as full of potential as ever.”

“I know there are many in China who think their time has come, that America’s best days are over, and there are probably some in this country who have lost confidence and think that China is the next best thing,” he said. “The real test of a nation is not how well it does when times are good, but how well it does when times are tough. The way I saw it from overseas, America’s passions remain as strong today as ever.”

In his 20-minute address, the former governor of Utah touched on human rights abuses in China and said that revolutions, business and technological innovations are still fueled and inspired by America.

Although Huntsman’s commencement address to the College of Arts and Sciences at the University of South Carolina was shorn of overt politics, it comes as he has stepped up his campaign efforts in the state.

Since leaving the Beijing post, Huntsman has been doing everything a man interested in a presidential run would do. On Friday, he met with South Carolina Gov. Nikki Haley (R), who emerged from their meeting saying that Huntsman is likely to be a serious candidate. He has also formed a political action committee for fundraising efforts and has been consulting with advisers with national campaign experience.

Next week he will head to New Hampshire, another crucial early primary state.

Huntsman, 51, echoed other Republican party leaders, saying that the GOP field for 2012 is far from set.

“There’s always room for a new voice,” Huntsman said Friday after he met with Haley. “To the extent that people are concerned about where we are, in terms of the economy and our relative position abroad, absolutely, people are looking for a new set of eyeballs.”

Out of the current field, Huntsman has the most international and White House experience, having worked for President Ronald Reagan and both Bush administrations.

Yet Huntsman faces two key challenges in a presidential bid: raising his profile and explaining his ties to President Obama to Republican primary voters who detest the administration’s policies, foreign and domestic.

“Let’s face it: It’s uphill for him because no one knows him and I really think the candidates who were here for the debate got a real bump and the ones who weren’t had to address why they weren’t, but nobody mentioned why he wasn’t here. He’s just not being thought about very much right now,” said David Woodard, a political science professor at Clemson University and GOP consultant. “The fact that he was selected by Obama — it might be a plus for running for president; it’s not for winning the nomination. To have this guy coming in saying he can talk to Democrats, that isn’t going to impress anybody.”

The conservative Web site the Daily Caller revealed last month letters that Huntsman wrote to Obama, calling him a “remarkable leader.”

Even as Huntsman prepared to deliver his address here, South Carolina Republicans were tallying the results of a straw poll that showed that Huntsman has ground to make up. Republicans gave former Pennsylvania senator Rick Santorum the edge over former Massachusetts governor Mitt Romney, 37 percent to 15 percent. Huntsman didn’t get enough votes to register a full percentage point.

For his part, Obama has approached a potential Huntsman candidacy in the same way he has a potential Romney run — damning them with faint praise.

“I couldn’t be happier with the ambassador’s service, and I’m sure he will be very successful in whatever endeavors he chooses in the future,” Obama said of Huntsman during a news conference with Chinese President Hu Jintao in January. “And I’m sure that him having worked so well with me will be a great asset in any Republican primary.”

Top Republicans have openly expressed some dissatisfaction with the field and have said a wild card could energize the race. Huntsman, who dropped out of high school to play in a rock band, could add a measure of cool to a field that has yet to find traction or a solid front-runner.

His speech was optimistic and hopeful, and he dropped a bit of his biography, including his flirtation with music when he had “hair that was Rod Stewart shaggy.”

“I wouldn’t wear anything but super skinny jeans,” he said. “I ended up leaving high school a bit early to play with a band called Wizard. I thought it was my ticket to fame.”

Woodard said Huntsman could add some charisma to the potential candidates and “looks like the guy who would play the president in a movie.”

“He has the manner and graciousness of a diplomat,” he said. “You could see him holding his own standing next to Obama.”

In his advice to graduates, Huntsman mentioned in passing his ambassador’s job, suggesting what he might say when asked to explain his tenure under a Democratic president.

“As much as you’re able, work to keep America great. Serve her if asked. I was. By a president of a different political party,” he said. “But in the end, while we might not all be of one party, we are all part of one nation.”