Pennsylvania votes in key contest
People in Pennsylvania are going to the polls today, to determine what will be a critical battle between Hillary Clinton and Barack Obama.
As the delegates are split in proportion with the vote, neither candidate is expected to win enough delegates to seal the nomination in the remaining primaries.
Pennsylvania is a key test for Clinton especially as she hopes it will sway some super-delegates her way.
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The state could be a decisive test in what has become an increasingly bitter fight for the Democratic nomination.
While Mrs Clinton is expected to win, analysts say she needs a convincing victory, ideally with a double-digit lead, to keep her campaign alive.
The latest polls show her ahead by between 7% and 10% in the state.
A Zogby survey released on Tuesday showed Mrs Clinton leading Mr Obama by 51% to 41%, while an InsiderAdvantage poll had her on 49%, with him on 42%.
Polling stations opened at 0700 (1100 GMT), with results expected soon after they close at 2000 (0000 GMT).
With four million registered Democrats, and 158 pledged delegates to the Democratic Party's nominating convention in August, Pennsylvania is the last of the big states to hold a primary.
Although Mrs Clinton is behind in the delegate count and in the total votes cast, she has won most of the big state contests.
And the white working class voters who have formed the backbone of her support so far are a significant constituency in the state.