A victory in Pennsylvania wouldn't allow Clinton to catch Obama in the number of pledged delegates, nor would it give Obama the delegates needed to win the nomination. Most pledged delegates are awarded proportionally based on the margin of victory in congressional districts, which vary in the total number of delegates allocated to them. Because of that, Obama or Clinton could win the popular vote yet not reach the delegates they need. But winning such a big state — one considered a key battleground in the fall — would strengthen the argument each is making to super delegates.
"You've got to get momentum for whatever is going to come afterward," Madonna says.
Clinton needs a Pennsylvania victory to make her case to the party that she could win big swing states in the general election. Obama, who is favored to win the Wyoming caucuses Saturday and the Mississippi primary Tuesday, will argue that he has won more nominating contests (27 out of 42 so far), more total votes (about 13 million to Clinton's 12.4 million, not including Florida and Michigan where primaries did not award delegates), and more pledged delegates.
"The super delegates will consolidate around that person who has the most delegates. We think that will be us," Obama said Wednesday as he flew to Chicago.
Both campaigns are organizing their ground game in Pennsylvania: The Obama campaign says it trained 1,900 volunteers last weekend and the Clinton campaign says it has signed up 1,500. Clinton will open eight offices in the state by week's end; Obama has five.
The issues in Pennsylvania aren't likely to be much different than those in next-door Ohio: the economy, the Iraq war and health care. Pennsylvania's unemployment rate is relatively low, but like Ohio it has lost manufacturing jobs.
"The issues that are in the forefront are in the forefront for a reason," says Bar Johnston, an Obama volunteer organizer from Center Valley, in eastern Pennsylvania. "It's really bread and butter issues."
Rep. Chaka Fattah, a congressman from Philadelphia and Obama super delegate, says opposition to the war in Iraq will be a key distinction for voters choosing between Obama, who opposed the war as an Illinois state senator, and Clinton, who voted to authorize the war as a senator from New York. He says opposition to the war is "one constant in Pennsylvania."
Madonna says the economy, as it has elsewhere in the country, has eclipsed Iraq in voters' minds.
"It'll be about the economy, health care and environmentally friendly energy. You cannot talk about the environment in Pennsylvania without talking about job creation," he says. "If you link it to that, it's pretty popular."
How did we get here?
Pennsylvania initially didn't figure to play much of a role in determining the Democratic nominee.
The primary calendar, which was moved up and squeezed together more than ever before, was designed to pick a nominee in a hurry. But two history-making candidates, both with lots of money and appealing to different demographics, sent that plan awry.
Obama's ability to galvanize crowds, attract new voters and get them to turn out, helped him win caucus states 11-2. Clinton's sway with state political establishments helped her win big states such as New Jersey, Ohio and California.