04/30/2008 05:12 am ET Updated May 25, 2011

Pennsylvania Primary Arrives: What's At Stake?

The Pennsylvania primary is underway today, and reports are already pointing to a big turnout. Even as Pennsylvanians go to vote, however, several reports are questioning the effect that today's results will have on the larger race.

What is really at stake? Once again, Hillary's win is not likely to be reflected in the delegate count, with a net delegate pickup perhaps no higher than 10. The Washington reports on the PA primary breakdown:

The state has a two-part primary ballot, with voters choosing a presidential candidate and also picking from a slate of local delegates. Essentially, each of the state's 19 congressional districts runs a separate contest for delegates, weighted according to turnout in recent elections. A total of 103 delegates will be awarded according to each district's popular vote, while the remaining 84 will be distributed according to the statewide popular vote, or as unpledged superdelegates. In Democratic strongholds, such as the 1st and 2nd districts, both in Philadelphia, participation rates are high, and those districts allocate seven and nine delegates, respectively.

Obama could win seven of the nine delegate at stake in the 2nd District, and four of seven in the 1st, his campaign estimates.

By contrast, the 12th District, in central Pennsylvania, where Clinton is expected to perform well, allocates five delegates; the 9th District, also pro-Clinton, awards three. Five other districts award four delegates each, while one (the 6th) awards six. Under party allocation rules, unless Obama loses by large margins in these even-numbered districts, he could split the delegate take.

And McClatchy reports that another key indicator for superdelegates, the popular vote, will still be a near-insurmountable hurdle for Clinton after the Pennsylvania primary:

With more than 25 million votes already cast, Obama leads Clinton by an estimated 13.7 million to 12.9 million, a margin of more than 800,000.

So even if Clinton managed to win Pennsylvania by the same 10-point margin she won in Ohio, more than current polls suggest, she'd emerge with only a 200,000-vote margin. That would leave her still trailing by more than 600,000 votes -- with no big states left.

Read HuffPost's full coverage of the Pennsylvania primary here.

Find out the latest poll results from HuffPost's Pennsylvania poll page.