During the course of the Pennsylvania primary battle, the candidates went bowling and drank beer, with Clinton going one step further and downing shots of whiskey and appearing more comfortable at times than her opponent.
Obama garnered unwanted headlines after suggesting economic realities have left people in the state "bitter" and clinging to guns and religion. Obama later admitted he should have worded his thoughts better.
Clinton was expected to win in Pennsylvania in part because of her edge in past primaries among blue-collar workers, those without a college degree, and older voters — all demographics representative of the Keystone State. Obama, meanwhile, had hoped his hold on younger voters and high interest in this primary from a record 218,000 newly registered first-time voters would erode some of her support.
"The state of Pennsylvania, on its face, given the nature of its voting population — older, white, Catholic, working class — for the most part, these are all demographic groups that Hillary Clinton has done well with throughout the course of this nominating process," Devine said.
Preliminary exit poll results indicate that nearly six in 10 Pennsylvania voters are women; under 50 percent of Pennsylvania Democratic voters have a college degree; three in 10 Democratic voters are Catholic; and almost half are liberals.
"To win this decisive, one candidate or the other, either Clinton or Obama, needs to break into the other candidate's base," Devine said.
If Obama bests Clinton in a state like Indiana or North Carolina where she is thought to have a strong base of support, Devine said, the race could shift in the Illinois senator's favor.
"If it doesn't, I think the race will continue the way it has since Super Tuesday, really, since Iowa and New Hampshire, just more of a see-saw than anything else, but one where Obama has been able to hold an advantage," Devine said.
Over a pancake breakfast at Pamela's Diner with his wife, Michelle, and owner of the Pittsburgh Steelers Dan Rooney, Obama said he doesn't expect the Democratic race to end until the last primary votes in June.
"I have come to the conclusion that this race will continue until the last primary or caucus vote is cast," Obama said. "And that's not far away."
Throughout the nominating process, Obama has done better than Clinton among young voters, urban voters, black voters and Democrats with college degrees.
As the polls opened in the Keystone State, both candidates got some last-minute jabs in on network and cable television interviews.
"I think there's a big burden on Sen. Obama... to prove that he can win a big state, because he hasn't really up until now," Clinton said in a pretaped interview with ABC's Chris Cuomo that aired on Tuesday's "GMA."
Clinton also decried Obama's fundraising advantage going into the state's primary. Obama outspent Clinton on TV in Pennsylvania by 2-1.
"I know very well that I'm in a real fight here," Clinton said. "Every time I turn around there are posters at bus stops and train trips and he's got an enormous cash advantage."