PHILADELPHIA (CBS) — It looks like Pennsylvania’s Senate race is turning into a dead heat.

For most of the summer and fall, Republican Pat Toomey has held a commanding lead in the polls, but now for the first time, a new independent poll shows Democrat Joe Sestak with a slight advantage.

The poll, from Muhlenberg College’s Institute of Public Opinion shows Sestak with 44 percent support, Toomey with 41 percent. The margin of error is five points. The poll was released on Wednesday, October, 20. Click here to view the full poll.

“Like most elections in Pennsylvania, the last two weeks are going to be pretty interesting,” said David Thornburgh, executive director of the Fels Institute of Government at the University of Pennsylvania. “Sestak’s case is helped by his suggestion that he can pull off the same kind of comeback that he did in the primaries.”

In the Democratic primary in May, Joe Sestak came from as many as 20 points back to defeat five-term senator Arlen Specter.

Political analysts say it’s important to remember that this is just one independent poll, and while it may show movement for Sestak, this race can still be won by anyone. Something echoed by a spokesman for the Toomey campaign.

“The polls are all over the place, with most of them showing a good sized lead for Pat Toomey,” said Toomey communications director Nachama Soloveichik.

“We have both candidates in this election not clearly one in front of the other. It’s sort of a toss-up,” said Drexel University political science professor Bill Rosenberg. But “the reality is it appears that the Sestak campaign has been gathering momentum as the campaign has been unfolding.”

The Muhlenberg survey is a daily tracking poll, which means it will be updated every day with new figures until the election, but it also means the sample size is smaller than most conventional polls. To get these results, 403 voters were surveyed between October 16 and 19.

Experts say it’s not clear what has caused Sestak’s movement. One possibility is his television commercials, especially one that uses Toomey’s own words against him. In the ad, Toomey is shown saying “My voting record is pretty hard to distinguish from Rick Santorum’s.”

Santorum lost his reelection bid in 2006 by 20 percentage points, largely because he was viewed as being too extreme says Rosenberg. He says Pennsylvania does not usually elect candidates at the extreme ends of the ideological spectrum.

“We have people that are willing to consider both candidates and in large part, the independents are going to decide this election,” he said.

So as the candidates head into the first debate Wednesday night, it truly is a race.

Reported by: Ben Simmoneau

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