SPRINGFIELD, Ill.- Gov. Rod Blagojevich holds a 10-point lead over his rival Judy Baar Topinka, but the governor’s support among voters appears to be weakening, according to a new statewide poll.

The telephone poll of 625 registered voters was conducted Sept. 19-21 by Mason-Dixon Polling & Research, Inc. of Washington, D.C. for Copley News Service, The (Springfield) State Journal-Register reported in its Sunday editions. The survey has a margin of error of 4 percentage points.

Forty-seven percent of people surveyed said they’d cast ballots in the Nov. 7 election for Blagojevich, a Democrat, compared to 37 percent who said they would vote for his GOP rival. Green Party candidate Rich Whitney garnered 4 percent, and another 12 percent were undecided.

But 40 percent of those surveyed said they had an unfavorable opinion of the governor – compared to 37 percent who said their opinion was favorable. Another 21 percent were neutral.

“His negatives are actually higher than his positives,” said Brad Coker, managing director of Mason-Dixon. “That’s always a sign of potential trouble.”

Experts said the poll highlights a window of opportunity for Topinka to cut into Blagojevich’s support in the six weeks before the election.

“She has to distinguish herself as a credible candidate,” said Kent Redfield, a political scientist at the University of Illinois at Springfield. “Neither one of them are in great shape, but he’s in probably better shape.”

Topinka is also struggling with perceptions of her, according to the poll, which found 29 percent of surveyed voters had a favorable opinion of the Republican. Thirty-seven percent had an unfavorable opinion and another 31 percent said they were neutral.

The survey found Blagojevich’s support is strongest in Cook County, while Topinka’s strongest showing was in suburban Chicago.