One of the aces that Mitt Romney believes he holds in the Palmetto State is the endorsement of Nikki Haley, the new 39-year-old governor who rocketed to political stardom last year by challenging the good-ol’-boy political network in the state. Fueled by endorsements from both Sarah Palin and Romney, Haley was able to marshal tea-party support to crush a sitting attorney general, a sitting congressman, and the state’s lieutenant governor, winning the GOP nomination and then the general election.

It was classic political Cinderella theater, with the story of the state’s first governor from a minority group (Haley is Indian-American) taking place on the 150th anniversary of its secession from the union and providing a powerful symbol of just how far the South has progressed. But one year after she was sworn in, enough of the luster has worn off that former governor Mark Sanford, her immediate predecessor and political mentor, is discouraged. “I wonder if she’ll be more of a liability to Romney than she is an asset,” he told me. “She’s taken her eye off the ball and lost focus.”

His comments are echoed by several tea-party leaders I spoke with, who say her efforts at cutting government have been half-hearted at best. “She is increasingly falling back in line with legislative leaders bent on preserving the old system,” says Brit Adams, a leader of the Upstate Coalition, a collection of tea-party groups in the Greenville area. “She talked about school choice and zero-based budgeting in the campaign, and now those things have dropped away,” says Talbert Black, the founder of Palmetto Liberty, a local political action committee.

Haley certainly has seen her approval ratings slump since being sworn in, although just how much is a point of dispute. According to a December Winthrop University poll, the governor’s approval rating is 35 percent, with only a little more than half of Republicans giving her a thumbs-up. Since every statewide official in South Carolina is a Republican, the GOP controls the legislature, and Republicans have a seven-to-one advantage in the congressional delegation, the Winthrop survey rang alarm bells everywhere.

The governor punched back. Appearing on NBC’s Meet the Press, she dismissed this “local poll” because it also showed that President Obama would today win South Carolina, which would be a bizarre result since he lost the state by 9 percentage points in 2008.

But the poll in question didn’t test President Obama’s general-election prospects in South Carolina, only his statewide approval rating.  This came in  at 45 percent — higher than Haley’s. The governor’s office was forced to admit she had misspoken.

“She sure didn’t have a problem with this ‘local poll’ when we correctly predicted her gubernatorial victory in 2010,” Scott Huffmon, the director of the Winthrop poll, commented, noting that his survey predicted Haley’s defeat of Democrat Vincent Sheheen in the general election. Nonetheless, Team Haley has a point when arguing that the survey is somewhat suspect. “I have consistently found a durable ten-point Republican-party affiliation edge in South Carolina elections,” says Haley strategist Jon Lerner. “The Winthrop poll surveyed 3.6 percent more Democrats than Republicans, so there was an inaccurate partisan weighing.”

That appears correct, but fixing it would still leave the governor with an approval rating only in the 40s, which is what recent private polls I was shown all pegged her at. A Public Policy Polling survey in September had her at 41 percent approval.

That level isn’t what an incumbent governor would hope for after a year in office. Even Governor Sanford, who crippled his own administration in 2009 when he admitted to leaving the state to meet his Argentine lover, ended his two terms in office a year ago with an approval rating near 50 percent.

“Everyone knows she has a weak governorship in which the major budget decisions are made by a five-member control board, on which she is only one vote,” says Ashley Landess, president of the free-market South Carolina Policy Council. “That said, she hasn’t taken on the power structure like her allies hoped, but rather accommodated herself to it.”

Chris Drummond, a former communications director for Governor Sanford, agrees. “The control board has a reform-minded state treasurer and state comptroller and two legislative committee chairmen and the governor on it,” he told me. “Too often the governor is voting to logroll with the legislative chairmen rather than voting for reform.” Although she will submit her own budget for the first time this month, her line-item vetoes of last year’s budget were minuscule and, in Sanford’s eyes, “prearranged” with legislative leaders. “She misled a lot of reformers. I regret my efforts to help her get elected,” Drummond told me.

Nikki Haley rode to prominence on a key issue in 2010. As a state representative, she bravely led the fight against legislative secrecy, pointing out that less than 8 percent of the bills passed by the legislature had a roll-call vote. She was ridiculed by Bobby Harrell, Speaker of the state house, who stripped her of a committee assignment and dismissed attempts to require roll-call votes “as a waste of taxpayer time and money.” But the issue of transparency resonated with the public and helped propel her to an improbable primary victory, with sleazy last-minute allegations of adultery barely slowing her down.