Poll: Toomey with 5-point margin in Pennsylvania Senate battle

(CNN) - On the eve of the midterm elections, a new poll indicates that Republican Pat Toomey has a five point advantage over Democratic Rep. Joe Sestak in the battle for Pennsylvania's open Senate seat.

According to a Quinnipiac University survey released Monday morning, 50 percent of likely voters in the Keystone State support Toomey, with 45 percent backing Sestak and five percent undecided.

Toomey's five point margin is within the poll's sampling error. Other surveys released in the past week also indicate a single digit advantage for Toomey.

The Quinnipiac poll indicates that Toomey has an overwhelming lead among Republican voters and has a 52 to 39 percent advantage among independent voters while Sestak has an overwhelming lead among Democrats.

"The candidates each hold their party bases pretty well, each getting more than 80 percent of the votes of their own party members," said Peter A. Brown, assistant director of the Quinnipiac University Polling Institute. "But it is independent voters, as is often the case in close elections, that swings the balance of power."

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 with both the Democratic Senatorial Campaign Committee and the National Republican Senatorial Committee spending millions on the race. President Barack Obama headlined a Democratic party rally in Philadelphia on Saturday.

In the battle for governor, the poll indicates that Republican nominee Tom Corbett leads Dan Onorato, the Democrats' nominee, 52 to 42 percent with six percent undecided.

Onorato, the chief executive of Allegheny County, and Corbett, the state's attorney general, are battling to succeed term-limited Democratic Gov. Ed Rendell.

The Quinnipiac University poll was conducted October 25-30, with 1,244 likely voters in Pennsylvania questioned by telephone. The survey's sampling error is plus or minus 2.8 percentage points.

–Follow Paul Steinhauser on Twitter: @psteinhausercnn