|Despite Clinton's considerable victory margin, Obama still holds the lead in delegate numbers|
After six weeks of frantic campaigning, increasingly bitter and brutal attacks on both sides, and millions of dollars spent in advertising by the candidates, Hillary Clinton has won Pennsylvania.
The so-called "Keystone state" lived up to its name on Tuesday, as record numbers of voters turned out to cast votes in the most important primary the state has experienced in decades.
"You know you can count on me," Clinton told a crowd of cheering supporters at a hotel in downtown Philadelphia as news of her 10-point margin of victory trickled in from the state's polling stations.
"Some people counted me out and said to drop out, but the American people don't quit and they deserve a president who doesn't quit either."
But despite a considerable victory margin, Barack Obama, the Illinois senator, still holds the lead in delegate numbers.
And the question remains whether the ongoing saga of the Democratic US presidential nomination remains a healthy example of true democracy at work, or a gruelling slog that is rapidly causing divisions within the party and among voters.
Earlier in the day Philadelphia's downtown played host to scores of Democratic supporters, with some polling stations experiencing lines from early morning as commuters rushed to cast their vote before heading to work.
Turnout among the state's estimated four million Democratic voters for the primary, the first in six weeks, was estimated at around 50 per cent, local media reported, a figure on a par with turnout in the country's presidential polls.
In the city scores of sign-wielding campaigners stood on street corners. One teenage boy sporting a sign urging voters to "Barack our world" while women wearing Hillary t-shirts, caps and badges chanted "Hill-a-ry" to passing cars.
However it was not all good natured.
Outside Philadelphia's first Baptist church in the city's centre a group of Hillary supporters became embroiled in war of words with Obama fans over Hillary's controversial comment during campaigning that she had assisted her husband in forging peace in Northern Ireland.
Comments were exchanged and for a moment the passions that have been stoked during this unprecedented primary campaign became all too stark.
As expected, Obama comfortably carried the urban centres such as Philadelphia and Pittsburgh with their sizeable African-American constituencies, while more rural areas in places such as western Pennsylvania, with the more white working-class vote, pitched for Clinton.
But although behind in the delegate count and lagging in fundraising, Clinton has won the US states considered key battlegrounds in US elections - Ohio, California, Texas and now Pennsylvania.
Analysts say Clinton has focused on this aspect of her electability in recent weeks during campaigning in the state in a bid to reach out to those so-called "superdelegates", or senior Democrat Party officials, who will vote for the nominee at the party's convention.
"Pennsylvania is essential for Hillary Clinton because the basic way she structured her campaign after Super Tuesday - when she didn't win outright - was to say she is the most electable candidate because she can win in those states that are truly Democratic and in those swing states where it can go either way," says Randall Miller, professor of history at Philadelphia's St Joseph University.
"Pennsylvania is the last state on that list, and [winning] allows her campaign to go forward and, not only that, it proves to voters she can tough it out."
Clinton referred to this issue of electability herself during a campaign stop on polling day in Pennsylvania.
"Why can't he close the deal?" she demanded of Obama at a campaign stop in Conoshoken, referring to the nomination.
"With his extraordinary financial advantage, why can't he win a state like this one if that's the way it turns out?"
A lengthy process
However, the prospect of a continuing nomination contest is one that concerns many in the Democratic party, not least because of the advantage some see the ongoing fight could be handing to the Republican presidential hopeful, John McCain.
"Republicans are just licking their chops at this, because their expectation is that some Clinton people - if Obama gets in - won't support him and the same in reverse for Obama," Miller adds.
|The protracted battle between Clinton and |
Obama has concerned some Democrats [AFP]
"They may not necessarily vote for McCain but they may sit out the election at least, and the key is where they are going to sit out the election, because if it is in some of these swing states then it gives a leverage that otherwise McCain wouldn't have."
Bill Anderson, a talk show host for Philadelphia's 900am WURD radio station, also says the result, although considerable, does little to change the status quo in the Democrat race and only prolongs the uncertainty.
"Unfortunately it was a victory that has allowed Clinton to continue, but hasn't really closed the delegate gap one way or the other, and it allows for a couple of weeks or so of the back-and-forth and beating-up on each other taking place," he told Al Jazeera.
Anderson also says that future primaries in Indiana and North Carolina will still not provide any firm answer to the nominee question, as the results will most likely balance out in Obama's favour whatever gains Clinton made in Pennsylvania.
And so the race is, still, not likely to end soon, he says.
"Clinton is very committed to stay in this race.
"And as long as there's no knockout blow delivered she'll take this to the convention and hope that she can swing the superdelegates as a nominee."