PITTSBURGH - Sens. Barack Obama and Joe Biden on Friday took the momentum from their party's convention -- and the sizeable poll bounce it produced -- and plunged deep into the heart of this economically depressed region, where they badly need their energy and economic messages to click.

The Obama-Biden ticket arrived in Pennsylvania with a strong push from their convention. A national Gallup poll conducted Tuesday through Thursday gave Obama a 49 percent to 41 percent lead over McCain. They had been tied last week.

The pair's trip to up-for-grabs western Pennsylvania included visits to a biodiesel fuel plant in Monaca, an ice cream store in Aliquippa and a rally in downtown Beaver.

"I want people here to know that I'm gonna be fighting as hard as I can for them and Joe Biden is gonna be fighting as hard as he can for them to create new jobs in high-growth industries like clean energy," Obama told a local TV reporter in Aliquippa.

More blue-collar cred?

These were the first stops on a Labor Day weekend tour of swing states, and Biden -- a Scranton native with a working-class background -- is hoping to help Obama rally reluctant supporters of Sen. Hillary Clinton, who did well here in the Democratic primary.

Obama is stressing economics and energy in this blue-collar industrial region. His first stop Friday, in Monaca, was at Pennsylvania Biodiesel Inc., a start-up company that will provide alternative fuel to trucking companies.

The visit was designed to spotlight both his energy program, which would invest $150 billion over the next 10 years in what Obama calls "affordable, renewable sources of energy," as well as his economic plan. He would end capital-gains taxes for small businesses and start-ups, saying they will "create the high-wage, high-tech jobs of tomorrow."

Chuck Gorman, a retired construction worker from North Hills, Pa., said he thought that Obama's speech was "too long" and that he is grudgingly supporting Obama despite his concerns about Obama's lack of experience because "I have no choice." But Gorman said the selection of Biden makes him more comfortable with Obama because Biden has experience -- and working-class Pennsylvania roots.

"You can't get much better than Joe Biden; he's a good man," Gorman said.

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