Obama drew the loudest cheers when he said it was time to bring U.S. troops home from Iraq, an overwhelmingly popular stance in the Democratic base.
He called the war "one of the biggest strategic errors in our military history" and said it had damaged the nation's standing as moral leader.
"When George Bush steps down, the entire world is going to breathe a sigh of relief," Obama said. "The world will welcome us because they want America to lead, not bully.. . . We still remain this beacon of hope for folks all over this world."
The rally was the populist portion of a daylong money call for Obama.
He had three more exclusive fund-raisers with big Democratic donors, concluding with a dinner at the Convention Center that had tickets going for $500 to $2,300.
Tickets to the Electric Factory rally cost $50 - $25 for students and seniors.
Mark Alderman, a Center City lawyer who is on Obama's national finance committee, estimated the campaign would net $500,000 all told in Philadelphia yesterday - a haul exceeding all of the money he had raised in the region so far.
Through March 31, Obama had raised $412,560 from Pennsylvania donors, compared with $446,975 for Sen. Hillary Rodham Clinton of New York and $432,000 for Sen. Joseph R. Biden Jr. of Delaware, federal campaign-finance reports show.
Obama also met for 30 minutes with Democratic mayoral nominee Michael Nutter at the Sheraton Center City Hotel, spokesman Robert Gibbs said. He declined to characterize the meeting.
During the primary, Obama had endorsed and stumped for one of Nutter's rivals, Rep. Chaka Fattah.
A spokeswoman for Nutter declined to comment on the meeting, saying it was private.
Although Obama's speech at the Electric Factory was standard stump fare - the same speech he would deliver, say, in Ottumwa, Iowa, home to the first nominating contests of 2008, minus the homage to ethanol - the content was almost beside the point.
Rather, the story was in the crowd, where people of all races and ages said that Obama inspired them with his idealistic talk about the politics of hope.
"He's the only one I believe when he talks - he's an honest guy," said Anthony Caroto, 33, of Havertown. "He's got to win. I can't explain it, but I think he would be a source of world peace."
Terron Green, 18, showed up outside the gate three hours before the event began and wound up in the front row below the stage.
"He will bring change, particularly to the schools," Green of West Philadelphia said. "Hopefully he'll be more involved in urban areas than this president has been."
Dawn Hockenberry said she had been an Obama fan since his 2004 keynote speech to the Democratic National Convention.
"I think the country needs somebody to be inspiring like John Kennedy," said Hockenberry, 57, of Center City. "He's the one."
Contact staff writer Thomas Fitzgerald at 215-854-2718 or firstname.lastname@example.org.