ONE WAY or the other, you are about to make history.

As the presidential campaign comes to a frenetic close today, Pennsylvania is ground zero for an election that will give America its first African-American president or its biggest upset in 60 years.

Addressing a crowd of 2,000 yesterday at Strath Haven High School in Wallingford, Delaware County, Republican John McCain was predicting an upset.

"I've been in a lot of campaigns, I know when momentum is there," Mc Cain said. "I sense it. I feel it. I know it . . . pundits have written us off, just like they've done before. My friends, the Mac is back!"

While McCain is finishing the campaign with a heavy presence in Pennsylvania, Democrat Ba-rack Obama is relying more on surrogates and a massive field effort to capture the state's 21 electoral votes.

Three polls last week gave Obama a double-digit lead in Pennsylvania, but a new NBC/Mason Dixon poll shows Obama up by only 4 points.

Though no Republican presidential candidate has carried the state since 1988, McCain has continued his blitz here in the campaign's closing days.

McCain was in Perkasie, near Quakertown, on Saturday, in the Philadelphia suburbs yesterday and was scheduled to be in the Pittsburgh area today.

Obama, apparently more comfortable with his position here than McCain, plans no appearances in Pennsylvania today.

But both Bill and Hillary Clinton will campaign for Obama separately in western Pennsylvania today, and Democratic vice-presidential candidate Joe Biden will rally at Marconi Plaza in South Philadelphia tonight.

The Obama campaign says that Biden will appear with a couple of members of the championship Phillies team, but spokesman Sean Smith said that their identities are "under our hat for now."

Meanwhile, the state Republican Party has begun airing hard-hitting TV ads attacking Obama and featuring his controversial former pastor, the Rev. Jeremiah Wright.

"If you think you could ever vote for Barak Obama, consider this: Obama chose as his spiritual leader this man," an announcer says, as the ad cuts to Wright shouting, "Not God bless America, God damn America!"

McCain had promised not to raise the issue of Wright in the campaign. McCain campaign spokesman Peter Feldman said yesterday that McCain "is not the referee of every political ad in this election."

McCain's appearance in Delaware County yesterday came only hours after his "Saturday Night Live" appearance. Mc-Cain traded in his suit for a tight black jacket with a popped collar and told the crowd that he's within a "couple points" of catching Obama in Pennsylvania.

U.S. Sen. Joe Lieberman, who appeared alongside McCain yesterday with former Pennsylvania Gov. Tom Ridge, U.S. Sen. Sam Brownback and others, said that Pennsylvania could determine the election.

"I don't want to put too much pressure on you folks," Lieberman said, "but let me just say that the future of the free world is on your shoulders."

McCain again ripped into Obama for wanting to "spread the wealth around" - a phrase he picked from the Democrat's conversation last month in Ohio to the ubiquitous Joe "Joe the Plumber" Wurzelbacher - and said that he would double the child deduction for working families, cut the capital-gains tax, and lower business taxes to help create domestic jobs and to keep U.S. companies from sending jobs overseas.

"Raising taxes makes a bad economy much worse. Keeping taxes low creates jobs, keeps money in your pants," he said - a phrase that caused some supporters to look at each other with cocked eyebrows, then awkward laughs.

"I'm gonna make government live on a budget, just like you do," McCain said.

Obama's Pennsylvania campaign director, Craig Schirmer, said in a memo that the campaign has had 57,000 volunteers mobilized to get out the vote in the closing days of the race.

"The visits of John McCain and Sarah Palin," he said, "can't compete with this grassroots organization." *