Photo by Jeff Swensen/Getty Images
A voter casts her ballot in the presidential primary Tuesday in Butler, Pa.

WASHINGTON — Women and older voters came out in force Tuesday in Pennsylvania's presidential primary, encouraging signs for Hillary Rodham Clinton as she sought a win to sustain her campaign.

Both groups have tended to support Clinton in previous states, and she needed their support once again. Pennsylvania was a must-win state for Clinton as she tries to overcome rival Barack Obama's lead in the race.

Should she lose, it would be a fatal blow to her candidacy — a defeat so unexpected that it would sap her arguments to remain in the race. It would be the dawn of a Democratic era minus the Clintons as the dominant force.

Clinton has been in must-win territory already this year — in New Hampshire and then Ohio — and both times she survived.

Another big victory could give her new energy in the face of calls for her to drop from the race to clear front-runner Obama's path to the nomination. It would enable her to argue she's had victories in most of the country's largest states, give her a chance at overtaking Obama's lead in the popular vote and boost her prospects heading into the final stretch of the campaign.

Interviews with voters leaving the polls showed almost six in 10 were women and three in 10 were age 65 or over.

Some voters had a hard time making up their minds. One in five said they decided for whom to vote within the last week and about one in 10 said they made up their minds Tuesday, according to the preliminary results of exit polling for The Associated Press and television networks.

A quarter of voters had household family income of more than $100,000 last year and about as many reported having a postgraduate degree. Those groups tend to vote for Obama.

There are seven states left to vote after Pennsylvania, and the candidates appear likely to split the spoils. Clinton is favored in West Virginia and Kentucky, while Obama is expected to take North Carolina, Oregon and South Dakota. Two states — Indiana and Montana — are competitive.

But Clinton has a tough reality to overcome to be nominated no matter what happens — Obama is practically assured to end the race with a lead in pledged delegates. Even in Pennsylvania, a Clinton victory was never bound to net her much in the delegate count since urban districts where Obama is strong have more delegates than those in rural areas where Clinton is likely to do well.

So winning the nomination will require Clinton to get unpledged superdelegates to look past the lead held by the candidate with a shot at becoming the first black president. Many of those superdelegates are elected officials who have constituents to answer to.

No matter what happens in the rest of the race, the odds are stacked high against Clinton winning the nomination. But Clinton has proven that she won't back down when she still has a shot, and a Pennsylvania win would give that to her.

Bill Clinton has already begun making a new argument for her candidacy — it's the Democratic Party rules that have kept her from becoming the nominee, he told a reporter on the eve of the vote.

The party rules split delegate support instead of allowing the winner of each state to take all the vote, as they do in the general election and in several states on the Republican side.

"We don't have a nominee here because the Democrats chose a system that prevents that result," the former president told The Washington Post.


Nedra Pickler covers the Democratic presidential campaign for The Associated Press.