The Quinnipiac University poll released Tuesday reflects a significant change in a hypothetical general-election matchup that the university found to be tied since last summer.
Peter Brown, the assistant director of the university's polling institute, said he could only assume Specter's campaign activity, such as mailings, or increased media coverage is responsible.
The survey shows Specter leading Toomey 49 percent to 42 percent, a substantial edge over the former Allentown-area congressman who narrowly lost to Specter in the 2004 GOP primary.
Toomey has been endorsed this year by the state GOP and is considered the front-runner for his party's nomination. The Toomey campaign said the poll is an anomaly compared to other polls that have put him ahead in the last six months.
The poll also says Specter maintains a decisive lead over U.S. Rep. Joe Sestak in the May 18 Democratic primary, 53 percent to 29 percent, a gap that has remained constant since May.
Sestak dismissed the result as reflective of a voter base that is not paying attention to the race yet.
His campaign, he said, has more cash on hand and better polling numbers than Toomey had when he took on Specter in 2004.
"We're a little ahead of where we thought we would be at this time," Sestak said Monday after a campaign event in Harrisburg.
The telephone poll of 1,452 Pennsylvanians was conducted during the week that ended Sunday. The sampling error margin is plus or minus 2.6 percentage points.
