The campaign now is less about persuading voters than driving them to the polls, including those in the vote-rich Philadelphia suburbs - home to one-fifth of the state's registered voters and about evenly split, with 748,000 Democrats and 721,000 Republicans.
The suburbs are among the most crucial battlegrounds this election. President Obama needs a huge Democratic turnout in Philadelphia. Romney needs a surge in rural and small-town Pennsylvania. Both need to rack up votes in Bucks, Chester, Delaware, and Montgomery Counties.
A Franklin and Marshall College poll last week showed the suburbs up for grabs. In 2008, Obama won all four counties by a combined 204,000 votes.
On both sides, there's a sense that ground-level operations can make a difference.
"If we win - when we win - we will have done it in the field," said Marcel Groen, the Democratic chairman of Montgomery County.
John Gibson, state manager for the Romney campaign, said field ops could have a large impact.
"I don't think we need to win the four suburban counties," he said. "I think we will do very well in them."
More is at stake than the presidency. Smith, the Republican nominee for U.S. Senate, has come from nowhere with $17 million in TV ads to seriously challenge Democratic incumbent Bob Casey.
Eighteen U.S. House seats are up for grabs in Pennsylvania, along with the offices of state attorney general, state auditor general, and state treasurer. Half of 50 state Senate seats are on the ballot, as are all 203 state House seats.
Seeing a late chance to snatch Pennsylvania away from Obama - and maybe take the Senate seat, also - national Republicans have been deluging the state with ads and phone calls. This has made the volunteers on each side dig in deeper.
Miriam Galper Cohen was doing computer entry Wednesday at the Obama field office in Elkins Park.
"It's tedious work, but I don't focus on the tedium," she said. "I care about getting out the vote for the president, and that means everything to me."
At 4 p.m., the sun was already dimming on Old York Road. The Obama campaign occupied two storefronts across from a Walgreens.
In one, it looked as if vandals had overturned the trash cans. At tables placed helter skelter, volunteers were checking leaflets promoting the Democratic slate to make sure they listed the right legislative candidates for various localities. The leaflets were to be put in door-hanger packets and distributed Monday.
In the second storefront, groups were hunched over corded telephones calling Obama supporters to recruit them for this weekend's get-out-the-vote operation, to be staged at a local pub. Sandwiches were in a back room.
Cohen, a psychotherapist, said this year's campaign feels different from 2008, when the Obama effort was practically a crusade.
"Because Barack Obama was the first African American to have the potential to be president, that was thrilling to me. This election doesn't feel thrilling to me. It feels like a necessity."
A two-member team of volunteers headed out to Leedom Street in Jenkintown, a modest neighborhood dating from the early 20th century.
Bob Wirtshafter, an energy consultant and former University of Pennsylvania professor, worked one side of the street. He said that even residents identified as Obama voters sometimes shut the door in his face.
He joked: "But I get rejected a lot less frequently here than I did when I was trying to get dates."
At one house with a Halloween skeleton, the voter he asked for wasn't home. But he met Bdeir Jasmina, a "Palestinian Israeli" who came to the United States 15 years ago.
Her husband, Khalid, and son, Magid, 23, can vote as new citizens, she said.
"I will vote next time," she promised. "I know my husband and son are excited."
The next day, 30 miles away in Paoli, Republican volunteers got a pumping up from Tagg Romney, 42, the oldest of Mitt Romney's five sons.
"The Democrats think they know how to turn people out; we have enthusiasm on our side," he told 25 to 30 people doing phone-banking.
The GOP office was behind a Burger King on Lancaster Avenue next to a vacant state liquor store. Parked out front was a white 1976 Cadillac, 19 feet long and decorated in Republican signs.
Candidate Romney himself planned to help the get-out-the-vote effort by appearing with other GOP candidates at an afternoon rally Sunday in Yardley.
Lori Hamilton said she needed no pumping up.
"I'm a volunteer junkie," said the Chesterbrook resident, a recent widow who on most days helps her daughter run a children's-clothing store in Paoli.
She said that calling voters gets harder and harder every election. "Young people, they have a tendency not to pick up the phone, just let it go to voice mail."
Joyce Macias, wearing a "Women for Mitt" button, said: "I'm going to be 80 years old my next birthday. I'm out pounding the pavement because I believe in Mitt Romney."
From the outside looking in, it's hard to get a grip on which side is doing better in field organizing.
Field operations were always considered a Republican forte in Pennsylvania. But Republicans admit they were outworked in 2008. They have been determined not to let it happen again.
"Our committee people and our soldiers are very energized," said John Kelemen, acting executive director of the Montgomery County GOP. "They are very energized. They are chomping at the bit."
Gibson, the Romney state manager, said Republicans have made 3.6 million "voter contacts" in just the last month.
GOP enthusiasm is shown in applications for absentee ballots, he said. By GOP count, as of Wednesday, 17,000 more Republicans than Democrats had applied for mail ballots.
Lifting all boats
A senior Obama campaign official, speaking Friday from Chicago, said Obama's field effort had a jump on Romney's partly because it has been under way since April of last year. Romney didn't become his party's nominee until this summer.
Jeremy Bird, the campaign field director, said Republicans have coordinated their get-out-the-vote efforts through state and national party groups.
Obama's effort has been more focused on Obama - but with the expectation that a rising tide lifts all boats.
"When we turn out people for the president, we are turning out people who are going to vote for Bob Casey," Bird said. "Bob Casey is going to benefit from that."
Neil Oxman, a veteran Democratic consultant, sees the election coming down to middle-income voters in older, near-in suburban communities like Havertown in Delaware County.
He imagines a couple in St. Denis Parish, Irish or Italian, in their 40s, living modestly with a home and cars they can afford - but feeling insecure about their future.
Both voted for Obama in 2008, as he imagines them. "The man has now gone" over to Romney. And the woman "is on fence."
Contact Tom Infield at 610-313-8205 or email@example.com, or follow on Twitter @tinfield.