WASHINGTON, 23 April 2008 — After six weeks of intense and sometimes nasty campaigning, the voters of Pennsylvania finally had their say.

Polls opened at 7 a.m. yesterday morning, and Sens. Hillary Clinton and Barack Obama made the rounds of the morning talk shows in last minute efforts to pitch for votes, and the 158 delegates at stake in this must-win state.

The Pa. primary drew to a contentious finish Monday as Clinton invoked images of Pearl Harbor and Osama Bin Laden in a television advertisement that questioned Sen. Obama’s ability to lead in a crisis.

Clinton warned voters not to “take a leap of faith or have any guesswork” when they vote, while the Obama campaign accused her of employing “the politics of fear.”

Obama currently leads Clinton 1,648 delegates to 1,504.

Neither candidate will pick up the 2,025 delegates needed to win the Democratic nomination before the convention, which will likely leave the Democratic super-delegates to decide the Democratic presidential nominee at the party convention in late August. Superdelegates are Democratic Party or elected officials who can vote at the national convention. They choose their vote and are not required to commit to a particular candidate before the convention.

Once considered the presumptive Democratic nominee, calls for Clinton to drop out of the race have increased from within the party as the candidates have stepped up attacks on each other. The increasingly pointed attacks have stoked fears among some Democratic leaders that the bruising primary battle could hurt Democratic chances in the general election.

“If she only wins by a few percentage points in Pennsylvania, it seals the deal for Barack Obama,” Dan Shea, director of the Center for Political Participation at Allegheny College, told reporters. “Clinton’s only chance is to change what people are saying about this race.”

“If Clinton wins by more than 10 points, which was her margin in neighboring Ohio and New Jersey, her campaign will have new momentum and she will soldier on,” said Bill Schneider, CNN senior political analyst. “If Clinton wins by single digits, we’re in a political twilight zone. Nothing changes.”

Clinton may be helped by the fact that Pennsylvania conducts “closed” primaries, meaning that only registered Democrats will be allowed to vote. Obama has benefited from the support of independent voters in previous primaries.

About 100 super-delegates remain undecided in the Democratic race, which means Clinton’s hopes of a comeback hinge on persuading most of them to support her campaign. And she can’t do that unless she trounces Obama in Pennsylvania and then performs well in upcoming contests in Indiana and North Carolina, observers said.

NBC political analyst Charlie Cook wrote in CongressDaily that Clinton finds herself in a no-win situation.” Even if she wins (Pennsylvania), she doesn’t really win in the sense of making a meaningful dent in Obama’s roughly 140 delegate lead unless she wins by over 20 or even 25 points.

“… Short of Obama completely collapsing, it’s hard to see how Clinton can still prevail but not at all hard to see how she gets outcomes today and perhaps in some of the future events that keep her in the race.”

Sen. Obama already conceded in media interviews that Clinton is likely to win in Pennsylvania. She spent election night with supporters in Philadelphia, while Obama flew on to Indiana which, along with North Carolina, votes in the next round of primaries on May 6.