As most experts predicted, Hillary Clinton defeated Barack Obama in Tuesday's Pennsylvania Democratic primary. Given his recent resurgence in momentum, however, many believed that Obama could close the gap to a respectable 5 or 6 percent. Instead, Clinton garnered a commanding 9.2 percent victory that will justify her extended stay in the increasingly volatile primary election. Although it is highly unlikely that Obama will lose the nomination, his inability to put Clinton away places his presidential run and the immediate future of the Democratic Party in serious peril.

Why couldn't Barack seal the deal? Here are the top five reasons:

The Debates

Seven days before the election, 1-in-5 Pennsylvania voters remained undecided; 58 percent of them ultimately voted for Hillary Clinton. A key factor in this outcome was last week's Democratic primary debate. Unlike the twenty contests that preceded it, last week's debate paid considerable attention to Barack Obama's recent scandals, flubs, and foibles. By spending most of the first hour discussing everything from flag pins to Bill Ayers, Clinton and her comrades at ABC successfully painted Barack Obama as an unknown and dangerous entity.  This, combined with the remaining racial anxieties surrounding Jeremiah Wright, played a considerable role in swaying still-undecided voters.

Key Endorsements

Given the Clintons' deep ties to the Democratic Party elite, Hillary was able to secure key Pennsylvania endorsements early in the race. In particular, Governor Ed Rendell (also the most popular mayor in Philadelphia history) and Pittsburgh Mayor Ed Ravenstahl served as powerful surrogates who helped to shore up Hillary Clinton's base in the Western part of the state. Philadelphia's new African American mayor, Michael Nutter (whom Obama did not endorse in the local mayoral race in favor of Rep. Chaka Fattah) helped to keep Obama's Philadelphia victory within an acceptable margin.

Barack's Lack of Street Smarts

In Philadelphia, Democratic candidates help to mobilize election day voters by paying "street money" to local operatives in order to get out the vote. This strategy, which is perfectly legal, is a tried and true method of getting the city's 3000 committeepersons to hit the block running. Citing philosophical and moral reasons, Obama elected to rely upon his unpaid volunteers rather than spending the half-million dollars that it would take to stimulate the local political economy. Although Barack won the city by 60 percent, he likely lost a sizeable chunk of voters due to his failure to feed the local Democratic machine. This decision not only reflects a failure to embrace the realpolitik --you think Hillary wouldn't have dropped some money on the block if she had the dough?— but also a deeper naïveté that could hurt him in November.

The Pennsyltucky Electorate

In order steal Pennsylvania from Hillary Clinton, Obama had to woo voters in the area known locally as "Pennsyltucky," or the region between Philadelphia and Pittsburgh where Southern-conservatism and deep racial and ethnic animus continue to inform public perception, policy, and practice. Unfortunately, as Obama argued in his infamous "bitter" remarks, Pennsyltucky residents often undermine their own material and political prosperity by voting their anxieties and fears rather than their interests. While the remarks themselves may have cost Obama a percentage point or two, they are merely symptoms of a larger problem. In addition to fetishizing wedge issues, Pennsyltuckyans also enjoy what Dubois referred to as "the psychic wages of whiteness," which allow them to close ranks around race rather than reason. Bottom line: poor white people don't want a black president.

Hillary's Working Girl Routine

Despite the razor thin differences between Hillary Clinton and Barack Obama with regard to economic policy, neither of which propose adequate relief to the nation's laboring class, the majority of Pennsylvania's working class voters sided with Hillary. Pulling from the Republican handbook of painting liberal Democrats as "latte sipping, Volvo driving, Ivy-League educated" elitists, Hillary Clinton has gone to extravagant lengths to refashion herself into a working class candidate. This strategy began in Ohio, where she miraculously convinced voters that she was anti-NAFTA at the same time that she substantiated her experience vis-à-vis her "central role" in a pro-NAFTA White House. In Pennsylvania, her performance reached carnivalesque proportions, as the Ivy-League grad and former First Lady threw back shots in local pubs, hung out in bowling alleys, and popped caps in the flesh of innocent ducks. In the process, Clinton not only endeared herself to working-class whites, many of whom were desperately looking for excuses to support a white candidate, but also positioned herself as a grassroots underdog refusing to back down against a deep-pocketed bully. This is evidenced by her insufferable victory speech, where she says that she was "up against a formidable opponent who outspent us three-to-one. He broke every spending record in this state, trying to knock us out of the race." Such tactics will galvanize working class voters in Indiana and give the super-delegates a legitimate consideration for the future: Can Obama win the working class vote?

Marc Lamont Hill is Assistant Professor of Urban Education and American Studies at Temple University.