8 Questions About The Pennsylvania Primary

One Republican described Obama's weakness as elitism. Another called it an "out-of-the-mainstream view of the world," and a third described his problem as a liberal-cultural disconnect of the kind that hurt John Kerry and Michael Dukakis in their elections.

Democrats put these controversies in class terms. They say Obama can gird himself against Republican attacks only if he connects with working-class voters with a strong economic message. "Unfortunately," wrote one Democrat, "hope will not trump the deepening recession as we go into the fall."

That's why Democratic strategists will be looking at Obama's performance in Pennsylvania. "If the returns from cities like Erie and Cresson indicate he still hasn't closed the sale with blue-collar voters, that would be a huge vulnerability for him," wrote Rick Sloan, communications director for the International Association of Machinists, which has endorsed Clinton.

Has Bill Clinton helped or hurt his wife's candidacy?

4. As one strategist put it, if Clinton were just an extremely bright senator from New York whose husband had not been president, she probably wouldn't even be in the race -- and certainly would not have started out as the prohibitive front-runner. He helped with fundraising, with providing a political network and with giving his wife the experience of operating in the White House for eight years.

"So in the largest sense, Bill Clinton has been of enormous help," the strategist wrote.

But increasingly there are those in the party who say Hillary Clinton has been weakened by the performance of her husband. "We all may have underestimated the depth of 'Clinton fatigue' in American," wrote one Democrat, who added: "Every time he steps up to the plate to defend Senator Clinton, he weakens her."

Some Republicans recognize the strength Bill Clinton has brought to his wife's campaign, but as strategist Mike Murphy put it, "He's yesterday in a change election and a distraction to her independent identity."

What is the most important remaining contest after Pennsylvania?

5. Indiana. It is the place where Obama, almost regardless of what happens today in Pennsylvania, could bring the long Democratic contest to a close.

Democratic pollster Mark Mellman wryly noted that the most important upcoming contest is "the one that has an unexpected outcome." In virtually all the other remaining states, either Obama or Clinton is clearly favored. Not so in the Hoosier State, whose primary is on May 6.

That same day, Obama is favored to win in North Carolina. If he manages to carry both states, the pressure on Clinton to quit the race, or certainly to signal that the competition is over, will be enormous. Of course, if Clinton were to win Indiana and pull off a victory in the Tar Heel State, then North Carolina would be seen as the state that changed the race.