PHILADELPHIA, Penn.--My, how things have changed.

The last time Stumper visited Philadelphia's Independence Mall--an expansive, grassy park in Old City bracketed by Independence Hall on one end and the National Constitution Center on the other--it was filled with 35,000 adoring Barack Obama supporters thrilling to the sounds of Will.i.am and, a little later, one of the candidate's patented perorations. That was three days before the Pennsylvania primary. Today, I returned the Constitution Center for a John McCain town hall--and found only a few hundred McCainiacs stationed before a sign that read "Citizen's Cafe" in a repurposed corner of the building's second floor.

McCain, however, couldn't have cared less. "I want to assure you," he told the cheering crowd. "I will compete and win in the state of Pennsylvania."

Much has been made of Obama's audaciously hopeful efforts to swing classically red states like Virginia and Colorado. But with his moderate brand and military cred, McCain has the potential to flip a few properties himself--and Pennsylvania, say experts and associates, is perhaps the best pick-off possibility of the bunch. On paper, it's easy to see why. In 2000, Al Gore beat George W. Bush by five percent, and four years later, only two points separated the incumbent president from challenger John Kerry. What's more, recent surveys show Obama leading, on average, by a mere 5.8 percent, with that slim margin sinking to two points in the latest poll. And finally, lest we forget, Hillary Clinton won the Pennsylvania primary by nearly 10 percent--despite Obama's massive rally on the eve of the election. So it's no wonder McCain chose Keystone country for his first blue-state stop of the general-election season. Black Eyed Peas do not a president make.

That said, McCain has his work cut out for him. At today's event, he was constantly oscillating between thoughtful moderation and thundering conservatism, as if he plans to win by being in two places at once--to Obama's right and his left. At the start of his speech, for example, McCain announced that, like Clinton, he would not shy away from painting the Illinois senator as an out-of-touch, unpatriotic elitist, reviving the dormant gaffe that had doomed Obama's chances with white, working-class Pennsylvanians back in April. (If it ain't broke, the saying goes, why fix it?) "We’re going to go to the small towns in Pennsylvania and I’m gonna to tell them I don’t agree with Senator Obama that they cling to their religion and the Constitution because they’re bitter," he said. "That's the reason why we're going to win the state of Pennsylvania next Nov. 4." Point taken. Seconds later, however, McCain seemingly decried the cheap-shot political culture that had blown Obama's slip entirely out of proportion, saying that "the American people are sick and tired of soundbites and spin rooms and 'gotcha' questions," and so is he.

Throughout his appearance, McCain made similarly jarring shifts every few seconds. First, he said, "I have always put my country first and his party second"; then he claimed (falsely), that Obama advocates "for a government takeover of health care." One moment, he was decrying policies that "give people who are very wealthy additional dollars when we have Americans struggling to keep their homes and find a job"; the next, he was accusing Obama of being a "typical tax-and-spend liberal." And so on. Still, while McCain has yet to find his voice on domestic issues--his response to a question about crime among teen girls veered from a Little Rock mentoring program to Nicaraguan drug lords to securing the Mexican border to the rural meth epidemic, then ended with the not-so-confident words, "I intend to enlist the help of the people who know these problems best"--he is undeniably powerful when speaking of the wages of war. "I know [Iraq] has been long, and hard, and painful," he said. "But veterans hate war more than anyone else. We know that there's nothing more painful than the loss of a comrade." The goal, McCain said, is peace, not war--a much more appealing message than "No Surrender." 

McCain will eventually find his rhetorical footing on domestic issues as well. But there are larger forces at work in Pennsylvania that might make winning impossible, no matter what he says or does. On April 22, as the New York Times' Frank Rich has written, "27 percent of Republican primary voters didn’t just tell pollsters they would defect from their party’s standard-bearer; they went to the polls, gas prices be damned, to vote against Mr. McCain. And while it was superfluous in determining that party’s nominee, 220,000 Pennsylvania Republicans (out of their total turnout of 807,000) were moved to cast ballots for Mike Huckabee or, more numerously, Ron Paul." To win, McCain has to bring these voters back into the fold while at the same time wooing "Democrats and Independents," as he promised to do today. It's not an easy task.

Meanwhile, Mcain's main Democratic target--former Clinton supporters, whom he made a point to "welcome" this afternoon--may prove more elusive than he expects. The most recent Pennsylvania polls, which put McCain within striking distance of Obama (as I noted above), were taken in mid-May, when Clinton's campaign was still alive and large numbers of Clintonites were threatening to defect. All told, my calculations showed that, thanks to these voters, McCain was doing about 7.5 percent better against Obama than he did against Clinton. But now Clinton has conceded and urged her backers to break for Obama. If you assume that many--not all, but many--of these Democrats will flow back into Obama's camp by November (and some already are) then Obama's actual lead is probably about double (10 or 12 points) what the polls showed last month. To make matters worse for McCain, the hotly contested Democratic primary race has given Obama a huge advantage in terms of organization and voter registration. In Pennsylvania, Dems now outnumber Republicans 4.2 million to 3.2 million; the party has gained 326,756 voters since a year ago (compared to a GOP loss of 73,009) and flipped the crucial Philadelphia suburbs from blue to red red to blue. In other words, the Keystone State is far less friendly to Republicans today than it was in 2004.

McCain, for one, is reveling in his underdog status. When the senator concluded his remarks here at the Constitution Center--"I want your vote. I need it. Pennsylvania will again be a battleground state"--a familiar song came on the PA: the theme from "Rocky." Not in regular rotation since New Hampshire, the track (real title: "Gonna Fly Now") seemed to signal that McCain is well-aware of the uphill battle ahead. Don't be surprised if you see him running up the Art Museum steps sometime soon.