The mainstream media has apparently reached a consensus regarding tomorrow’s Pennsylvania Democratic presidential primary: Clinton will win, and the only question appears to be margin of victory.

Maybe. Buried in the most recent polling data compiled at Real Clear Politics is one anomalous outlier. While the RCP poll average indicates a Clinton margin of 5.9%, the final Pennsylvania numbers from Public Policy Polling (PDF file) has Obama leading by three percentage points. Of all the polls reflected in the RCP average, the PPP poll sample of 2338 registered Democrats is more than double the sample size of the second largest (the Quinnipac poll), and more than three times the sample of the other polls used in the RCP average. The large sample size provides the PPP poll with a margin of error of 2%.

Public Policy Polling’s final polls before the Texas and Ohio primaries were uncannily accurate. They had projected a Clinton margin of 51% - 42% in their final Ohio poll. The 5% undecided broke 60/40 for Clinton in Ohio to provide the official margin of 54% - 44%. Texas was a similar story. PPP had Clinton up 50% - 44%, although in Texas the undecided segment in the final PPP poll moved strongly towards Obama, resulting in the 51% - 47% official tally for Clinton. PPP’s final Keystone State poll shows Obama leading 49% - 46%, with 5% still undecided. If we assume that 60% of these voters move to Clinton, Obama would eke out the slimmest of victories: 51% to 49%.

Adding to the uncertainty of the Pennsylvania primary are the extraordinarily swelled ranks of registered voters. Politico reported today that 217,000 new voters have registered since January, and the vast majority of these have been Democrats. There have also been 178,000 voters who have switched party affiliations, and an astounding 92% of the party jumpers have moved to the Democratic side of the fence. This means that 7% of the now four-million plus registered Democrats in Pennsylvania are new additions, and these are the types of voters who have strongly supported Senator Obama in prior contests. Whether Obama maintains this trend in Pennsylvania may determine not only the outcome of this particular race, but could also provide some insight into how deeply he’s been affected by the Wright controversy, ‘bittergate’, and the controversial debate performance in Philadelphia last week. There is no doubt that Senator Obama has been scuffed up by the increasingly contentious Democratic primary fight. Pennsylvania may very well demonstrate whether those effects reach beyond the punditocracy.

The warring camps are of course spinning like gyroscopes today. Clinton Communications director Howard Wolfson lowered expectations while arguing, “If Sen. Obama can’t win a big swing state with that enormous spending advantage, just what will it take for him to win a large swing state?” Obama himself refused to predict victory, commenting in a Pittsburgh radio interview that, "I’m not predicting a win. I’m predicting it’s going to be close and that we are going to do a lot better than people expect."

We’ll all know soon enough. Don’t be surprised though, if the PPP poll presages the end of the Clinton campaign. A narrow Obama victory would almost certainly lead to the suspension of the once-inevitable candidacy of Hillary Rodham Clinton, and even a victory may not be enough to keep her afloat. Passing with little notice among the relentless media build-up towards tomorrow’s election, was the announcement that the Clinton campaign began April with 9 million dollars in cash available for the primary cycle, and 10 million dollars in debt. That’s right. Read it again. That’s a million dollar deficit to start the month. In no little contrast, the Obama machine began April with 42 million dollars available to spend in upcoming primaries, and a paltry $650,000 in debt.

Those numbers are not likely to shift towards Clinton’s favor even with a victory in Pennsylvania, and the delegate math is daunting even if she somehow manages a blow-out. Public Policy Polling’s final poll may be an outlier in suggesting an Obama victory, but none of the polls are indicating a Clinton landslide.