(Image Credit: Carolyn Kaster/AP Photo)

MT. HOLLY, N.C. - President Obama's 13 th official visit to this key swing state is set against the backdrop of a frustrated electorate whose support will likely be the most difficult for Obama to recapture in November.

Obama won North Carolina in 2008 by the narrowest margin of any state - just 14,000 votes, or 0.3 percent.  But his standing among voters here has only slipped in the three years since.

A new Elon University poll of Tarheel State residents shows Obama's job approval rating underwater, with just 45 percent giving him a thumbs-up overall and fewer, 43 percent, giving him the same for his handling of the economy.

A majority here - 51 percent - disapprove of Obama's handling of the economy, a not unsurprising figure given that North Carolina's 9.9 percent unemployment rate was the fifth-highest in the country in December, according to the Labor Department.

"His future here in the state is closely tied to the economy," said Mileah Kromer, a political science professor at Elon University and director of the school's poll.

"That is what North Carolinians are most concerned about, and I think voter turnout will be tied to it. The key will be whether or not an upward trend continues and the perception that things will improve," she said.

The Obama campaign has nine offices open across the state, recruiting volunteers, organizing canvasses and registering voters for the fall. Aides say added spotlight on the state with the Democratic National Convention planned for Charlotte in September will also help raise Obama's profile.

First lady Michelle Obama and Vice President Joe Biden have also made recent trips to the state to buck up supporters and raise cash for the convention and the 2012 campaign.  They are also enlisting the support of North Carolina native son James Taylor.

But in spite of the push, even some Democrats are publicly skeptical of Obama's claim to North Carolina's 15 electoral votes.

Obama "will probably lose North Carolina," former Democratic National Committee chairman Howard Dean told The Nation last month.  Dean added, however, that he thinks Obama will still pull off a narrow re-election.

This post has been updated from an earlier version.