Tom Bevan

is a cofounder and the executive editor of RealClearPolitics

If you're looking for ways to boil the 2012 presidential race down to its simplest form, here's one of the easiest: It's nearly impossible to envision any way Barack Obama can win reelection next year if he loses Pennsylvania. No Keystone State, no second term. It really is that simple.

Right now, things are looking dicey for the president in Pennsylvania. Though national polls show the president enjoying a bump in his job approval rating because of Osama bin Laden's killing, most experts don't expect the boost to last. Moreover, Obama's ratings on the critical issues in next year's election - the economy, jobs, government spending, and the deficit - remain low and haven't budged at all in the latest round of polling.

Which brings us back to the president's ongoing struggles in Pennsylvania. Last month, the Democratic polling firm Public Policy Polling released a result in which Obama's job approval rating was just 42 percent among Pennsylvania voters.

Two weeks ago, Quinnipiac University confirmed PPP's finding with an identical presidential job rating of 42 percent in its own Pennsylvania poll - a new low for Obama.

Worse still for the president, for the first time the majority of Pennsylvania voters in the Quinnipiac poll said Obama did not deserve to be reelected.

The Quinnipiac poll showed a sharp decline in Obama's standing in Pennsylvania between February and April - particularly among independents. In mid-February, independents approved of the job Obama was doing as president by a 4-point margin, 50 percent to 46 percent. By late April, their opinion had flipped: They disapproved of the job he was doing by a 20-point margin, 37 to 57.

What caused independents to sour so dramatically on Obama in those nine weeks? That's hard to say for sure, but a continued sluggish economic recovery, rising gas prices, a nasty partisan fight over the budget, and a hastily planned military intervention in Libya that appears to have bogged down into a stalemate all probably took a toll.

The high marks Obama has received for his leadership in the killing of bin Laden may help the president recover some ground with independents on issues such as national security and his handling of Afghanistan. But the economy remains a sore spot, and it's an issue where Obama seems to be coming up short with voters.

G. Terry Madonna, director of the Center for Politics and Public Affairs at Franklin and Marshall College, says Obama's demeanor and perceived lack of empathy might also be creating a disconnect with the state's independent voters.

"Like Obama or not," says Madonna, "he just doesn't relate very well. He hasn't been very good or very sensitive on matters of the recession."

Obama's trouble with independents in Pennsylvania is no small matter, because most experts believe he can't win the state without them.

The bulk of Pennsylvania's independent voters are clustered in the four counties surrounding Philadelphia and two counties in the Lehigh Valley (Berks and Lehigh).

These voters are best described as quintessential suburbanites - more moderate and less ideological in their views, more liberal on social issues but more conservative on fiscal matters.

Obama cleaned up with this bloc in 2008, winning all six counties by large margins en route to an easy 11-point state victory over John McCain.

But these independents moved heavily back toward the Republicans in the 2010 midterms: Democratic Senate candidate Joe Sestak and Democratic gubernatorial candidate Dan Onorato carried only two of the six counties. Both men lost.

Right now the one bright spot for Obama is the perceived weakness of the Republican field. Despite the president's horrid ratings in Pennsylvania, he's still running even with or ahead of most of the prospective GOP candidates.

Still, this election will first and foremost be a referendum on the president. If Republicans nominate a candidate who isn't viewed as "out of the mainstream," Obama will face a significant challenge in recovering ground with Pennsylvania's independent voters.

It's a challenge with dire consequences.

"If Obama can't win Pennsylvania, he will almost certainly lose Ohio and Florida," Madonna says.

And if Obama can't win any of those "Big Three" battleground states in 2012, it's very hard to see him winning back the White House.

E-mail Tom Bevan at tom@realclearpolitics.com. A version of this article appeared on realclearpolitics.com.