Democrats Hillary Clinton and Barack Obama battled to the bitter end on Tuesday for Pennsylvania's presidential delegate prize, launching a barbed ad campaign and working crowds for every vote up to the last minute. ( dpa )
Pennsylvania voters turned out in brisk droves with the economy and health care on their minds and the fate of Hillary Clinton's presidential ambitions in their hands.
Election results are expected after 0030 GMT Wednesday.
After six weeks of contentious bidding for the state's large delegate prize, Senator Clinton, 60, was hoping for a strong enough win against Senator Obama, 46, to withstand demands that she step aside and to gain momentum for races in the remaining seven states and two US territories.
Pennsylvania's 158 delegates are up for grabs, and Clinton's double-digit edge from some weeks ago has been shaved to 5 per cent by Obama, who has outspent her on advertising more than two-to-one.
Clinton used her final TV ads to appeal to national security worries among voters, showing images of al-Qaeda terrorist leader Osama bin Laden, World War II and economic crises.
The ad drew a rebuke from Obama campaign spokesman Bill Burton, who charged that Clinton was playing the "politics of fear" and compared her to US President Bush for invoking bin Laden "to score political points."
At a polling station near this fabled chocolate-factory town of Hershey, the uppermost issues for voters were health care and the economy, and they cited the daily jumps in the price of petrol.
Pennsylvania's economy - which ranges from heavy industry to gentle farmland and mines - has dropped into negative growth figures as the rest of the country limps barely in the positive zone.
Those worries, particularly among the eastern state's large number of blue-collar workers, and Clinton's family ties to the state were expected to give her the edge over Obama.
"If it's gas or a candy bar, what would you do?" said one 57-year- old Hershey employee who works in product development. He didn't want his name used, nor would he say whom he voted for.
The intense campaigning in Pennsylvania has inspired an added 500,000 voter registrations, considerably boosting the state's total number to more than 7 million.
Most of the new registrants are Democrats, including about 160,000 who switched from centre-right Republican to the centre-left party, Democratic Party national chair Howard Dean said in broadcast remarks Tuesday.
For many Democrats, the Obama-Clinton choice was difficult.
"It was very tough," said Kathy Brode, 50, a teacher who waited until Monday to decide to vote for Clinton. "Ultimately I went for the person who I believed had a little more experience."
An ardent Clinton supporter, Suzanne Brinser, 40, said she thought the drawn-out battle between Obama and Clinton - seeking to become the first African American or woman in the White House - has not hurt the Democratic Party.
"Sometimes we've got to go through pain to gain, and if it's for the right person to be the nominee, it's absolutely necessary," she said after casting her vote.
Other people were wary of Hillary's ties to the administration of her husband, former president Bill Clinton.
"I like change. We've had enough of the Clintons," quipped Antonio Ortenzi, 77, a retired Hershey chocolate factory worker.
Nationally, Obama has a small lead of 150 delegates in the race to the Democratic nominating convention in August, where 2,025 delegates are needed to reach majority.
Even if Clinton falls short of a knockout win in Pennsylvania, she has indicated she won't back down.
Just a few weeks ago, national Democratic Party leader Dean hinted it might be a good idea if she did just that, to avoid a bitter internal battle that could serve Republican nominee-apparent Senator John McCain on November 4.
On Tuesday, however, Dean said that "of course" no one should drop out of the race, and that the heated attention was good for the party.
Obama's strengths are among the younger voters - many registering for the first time energized by his campaign - and in the urban Philadelphia area. Clinton has drawn support from Pennsylvania's older voters, blue-collar workers and women, and she has home-field advantage through family connections in the north-east of the state.
McCain wrapped up the centre-right Republican presidential nomination last month, but his name was still on Pennsylvania's ballot along with other Republican presidential candidates who have dropped out.