From RCP:

Despite favorability ratings still hovering in the 30s, North Carolina Sen. Richard Burr (R) leads four Democratic challengers in his bid for re-election to a second term, according to a new survey from the Dem-leaning Public Policy Polling. Burr leads Secretary of State Elaine Marshall, state Sen. Cal Cunningham, lawyer Kenneth Lewis and Chapel Hill Mayor Kevin Foy.
Burr wins 43% against all four candidates — identical to the 43% former senator Elizabeth Dole (R-N.C.) won against Kay Hagan (D) in August 2007. Hagan, of course, went on to defeat Dole in the 2008 general election.