According to PPP, Beitler's biting into Marshall as much or more than he's biting Burr:
Burr's at 38% to 33% for Marshall and a surprising 10% for Libertarian Michael Beitler. Beitler's running basically even with Burr and Marshall among independents, getting 26% to 29% for the Democratic challenger and 27% for the Republican incumbent. Contrary to conventional wisdom about where Libertarian candidates get their support from Beitler is actually pulling 7% of Democrats to just 4% of Republicans. Beitler may be doing well with conservative Democrats who don't want to give Barack Obama another vote in the Senate but who don't much care for Burr either.
The punditry has stated time and again that one reason the 2010 North Carolina Senate race won't be a repeat of the 2008 contest is that Burr has been much more visible than Dole was, but someone forgot to tell the voters that. 41% of North Carolinians think that Dole was more visible as a Senator than Burr has been to 32% who think Burr has been more visible, and 27% with no opinion. The feeling that Dole was more visible is held by Democrats, Republicans, and independents alike.
Burr's relatively anonymity for an incumbent Senator can be seen in his approval numbers. 28% of voters still have no opinion of him, with those who do splitting negatively. 34% like the job he's doing while 39% disapprove.
Marshall is still pretty unknown too despite 14 years in statewide office and a recently completed campaign to secure her party's nomination. 58% of voters have no opinion about her with 22% seeing her favorably and 20% unfavorably.
PPP notes that, at this stage in the '08 Senate race, Republican incumbent Elizabeth Dole led Democratic challenger Kay Hagen by 14 points — and Hagan won.
Bottom line: Burr's no shoo-in, and Marshall's upside potential is good.