A new poll shows Roy Cooper ahead in 2010.
Cooper has not yet said whether he will run, but he is widely considered the frontrunner among potential Democratic candidates. A recent Civitas poll found Cooper leading Burr 41-38.
The poll also found Burr had a 35/31 percent favorable/unfavorable rating, compared to 41/20 for Cooper.
"If Roy Cooper enters the race for US Senate this race automatically becomes a tossup, if not even slightly Democratic leaning," said president Dean Debnam in a statement.
The poll also found Burr leading Democratic Rep. Mike McIntyre, 39-34.
The automated survey of 979 registered voters was taken from April 8-11. The margin of error is plus or minus 3.1 percentage points.