(CNN) - Six days before the midterm elections, a new poll indicates that it's too close to call in the fight for an open Senate seat in Pennsylvania.
According to a CNN/Time/Opinion Research Corporation survey released Wednesday, Republican nominee and former congressman Pat Toomey holds a 49 to 45 percent advantage over Rep. Joe Sestak, the Democrats' nominee, among likely voters in the Keystone State, with six percent undecided or backing another candidate. Toomey's four point margin is within the poll's sampling error.
Full results (pdf)
Other surveys out in the past few days have ranged from an eight point Toomey lead in a Franklin and Marshall survey to the two candidates dead even in a Reuters/Ipsos survey.
The CNN/Time survey indicates that Toomey leads 88 to 6 percent among Republicans and holds a 54 to 41 percent advantage among independent voters while Sestak leads 87 to 8 percent among Democrats.
"About one in four self-described independents say they support the Tea Party movement, and Toomey is winning handily among that group," says CNN Polling Director Keating Holland. "What's keeping Sestak's hopes alive is his 14-point lead among independents who don't support the Tea Party."
In a sign that enthusiasm for voting appears to be on the Republican side, when expanded from those likely to vote to the larger sample of all registered voters, Sestak holds a 47 to 43 percent advantage, with five percent undecided.
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.
"Sestak, like several other Democrats running for Senate this year, is having trouble connecting with women," Holland adds. "Sestak and Toomey are essentially tied among women. Democrats rarely win statewide races unless they can win a solid majority of the women's vote."
In the battle for governor, the poll indicates that Republican nominee Tom Corbett leads Dan Onorato, the Democrats' nominee, 52 to 45 percent with three percent either undecided or backing another candidate.
Onorato, the chief executive of Allegheny County, and Corbett, the state's attorney general, are battling to succeed term-limited Democratic Gov. Ed Rendell.
According to the survey, Corbett leads by 15 points among independent voters.
President Barack Obama headlines a Democratic Party rally in Pennsylvania on Saturday. According to the poll, 43 percent of likely Keystone State voters approve of job Obama's doing as president, with 52 percent saying they disapprove. Among the larger sampling of registered voters, 46 percent approve and 47 percent disapprove of how the president's handling his duties.
The CNN/Time/Opinion Research Corporation poll was conducted October 20-26, with 1,517 adults in Pennsylvania questioned by telephone, including 1,310 registered voters and 823 likely voters. The survey's overall sampling error is plus or minus 2.5 percentage points, with a sampling error of plus or minus 3.5 percentage points for likely voters.
–CNN Deputy Political Director Paul Steinhauser contributed to this report