(CNN) - A new poll indicates that Republican Pat Toomey has a 7 point advantage over Democratic Rep. Joe Sestak in the battle for Pennsylvania's open Senate seat.
According to a Franklin and Marshall Center for Opinion Research survey released Wednesday morning, 43 percent of likely voters in the Keystone State support Toomey, with 36 percent backing Sestak and a large 19 percent undecided.
Toomey's seven point margin is just within the poll's sampling error and is down from a 9-point advantage he held in a Franklin and Marshall survey from last month.
Among the larger sampling of registered voters, Toomey's margin shrinks to 37 to 35 percent, with nearly three out of ten undecided.
Other recent surveys released over the past two weeks indicate a closer contest between the two candidates.
Earlier this year Sestak, a former admiral and two-term congressman from southeast Pennsylvania, came from behind in the polls to defeat Democratic Sen. Arlen Specter for the GOP nomination. When Specter switched parties last year, he cited the difficulty in winning the Republican primary against Toomey as a factor. Besides his service in Congress, Toomey is also the former head of the Club for Growth, a limited-government and anti-tax organization, and he enjoys the support of many in the Tea Party movement.
Both parties are concentrating a lot of firepower on Pennsylvania. The Democratic Senatorial Campaign Committee has spent more than $4 million on ads in the state since mid August. When all is said and done, the DSCC's counterpart, the National Republican Senatorial Committee, is expected to spend roughly $5.5 million in Pennsylvania in support of Toomey.
The Franklin and Marshall poll was conducted October 18-24, with 720 Pennsylvania residents, including 631 registered voters, questioned by telephone. The survey's sampling error is plus or minus 3.7 percentage points for registered voters and plus or minus 3.9 percentage points for likely voters.
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