Turnout is being seen as the key to victory.
Phone banks are just a part of the orchestrated mass activity at Obama's Center City field operation office.
Volunteers poured in and out of there by the hundreds on Monday, heading off to assignments. Many have come in from states like New York and Maryland where Obama victories are considered a forgone conclusion.
Bill Robinson has worked in every presidential campaign since the early 70's. He's never seen a machine this well-oiled and fined tuned.
"I think this is the most disciplined campaign I've ever worked in," Robinson said. "I've been working in campaigns since the McGovern campaign in '72, and I've never seen on like this."
Obama '08 is counting on thousands of volunteer canvassers out on the street, in the city and suburbs going door to door, to generate turnout. More than 800,000 Democrats are registered in Philadelphia. Massive turnouts and pluralities in the city and surrounding suburbs are what this campaign this campaign is counting on in the battle of Pennsylvania.
Behind in the polls, the McCain-Palin campaign is giving no ground here in the suburbs. The phone banks are operating at full tilt.
And while volunteers in-house and out canvassing door to door cannot match the foot soldiers Obama has, they're not giving up. Delaware County, for example, had been a bastion of Republican machine discipline. But that has been slipping during the last 4 presidential cycles.
The conventional wisdom is Obama needs to carry a lead of about 500,000 votes in Philadelphia to ensure victory in Pennsylvania.