While no Democrat has actually stepped forward with a serious challenge to Sen. Richard Burr (R-N.C.), that doesn't mean the generic Democratic candidate doesn't lead the first-term senator in polling. A new survey from Public Policy Polling (June 12-14, 784 RV, MoE +/- 3.5%) finds Burr trailing an unnamed "Democratic Opponent" 41%-38%.

Just 64% of those who said they were conservative and 49% of Republicans said they would back Burr over a generic Democrat.

Attorney General Roy Cooper and Rep. Heath Shuler were once the leading Democratic contenters to take on Burr, but both have taken their hats out of the ring (Shuler twice), leaving Democrats with what looks like a vulnerable incumbent to challenge but with no challenger to do it.

In the survey, 29% said Burr deserves a second term in office, while 49% said it's time to give someone else a chance. Just 34% approve of the job Burr's doing in the Senate, compared to 35% who disapprove and 31% not sure.