PHILADELPHIA -- Sen. Hillary Rodham Clinton, clinging to a lead in the polls, made a final push across the state yesterday in search of the votes to keep her presidential aspirations afloat.

"If there were ever any doubt about what difference a president makes, the last seven years have erased that doubt," she told a cheering crowd of 5,000 late last night in Philadelphia.

Mrs. Clinton has held onto a lead in statewide polls, but needs a good showing in the state today to carry on with her campaign.

In Philadelphia, where she was accompanied by her husband, former President Bill Clinton, and her daughter Chelsea, she made one last plea for supporters to talk to their friends about her.

Mrs. Clinton's first stop in long, grueling day was a midday rally in Market Square, before going on to Harrisburg and then Philadelphia, where she spoke at the Palestra, the storied basketball arena on the campus of the University of Pennsylvania,

In Pittsburgh's Market Square, where the former president was called on to hold the crowd in place as her campaign plane circled the skies an hour late, Mrs. Clinton urged rally-goers "to go to the polls and vote for me for the toughest job in the world. I want you to think of this as a hiring decision."

With just hours to go before the largest of the remaining 10 primaries in a so far indecisive nominating process, some of the voters were still making their "hiring" decisions. That included some in the very crowd that cheered Mrs. Clinton yesterday.

"I'm here more for historical reasons," said Joanne Lacher, a Penn Hills barber who, a Hillary button on her lapel notwithstanding, said she has yet to decide.

Her dream would be a Clinton-Obama, or Obama-Clinton, ticket.

In an election that could yet turn on undecided voters, a surprising number seemed to be in Market Square.

"I'm leaning toward Obama right now, but just marginally," said Jim Fusetti, a South Hills retiree. "Right now I probably won't know until I walk in and decide to cast my vote right there."

Cliff Kelley, of East Liberty, had his mind made up.

"I liked Hillary for a long time. I thought she didn't get a fair shake when she got into the office with Bill," said Mr. Kelley, who praised the former first lady's efforts for national health insurance.

"This woman was in there for eight years with her husband. When he had a problem you know who he talked about it with -- he talked about it with her about it. So she was on the front lines for eight years," he said.

In Philadelphia, Shincy Shevu, 20, a junior pre-med student at Penn from Philadelphia was attending the rally with a friend, said she was undecided. "She's got more experience, but Obama is very charismatic. He's talks a lot but doesn't really say very much. She is more detailed on the issues."

At Harrisburg's Shriners' auditorium, Mrs. Clinton appeared with her biggest Pennsylvania supporter, Gov. Ed Rendell. "When she becomes our next president, we'll have to add a new phrase to our lexicon -- Madame President,'' gushed Mr. Rendell.

Mrs. Clinton urged the crowd to "spend the next 24 hours reaching out to as many people as you can."

In Pittsburgh, the act of introducing the former president set off a small storm when Pittsburgh Mayor Luke Ravenstahl and Allegheny County Chief Executive Dan Onorato -- both prominent Clinton backers -- took the stage and began their introductions of the former president.

They overlooked another prominent Clinton supporter on the stage, Lt. Gov. Catherine Baker Knoll, who wrested the microphone from Mr. Onorato and let fly with a complaint picked up over the loudspeaker.

As Mr. Clinton mounted the steps to the stage, Mrs. Knoll said: "They never recognize the lieutenant governor. These two men can't stand women. You know what? I have loafed with this president and with Hillary and their beautiful daughter Chelsea for 25 years. That's long before he was the governor -- that's governor of Arkansas."

She later said she apparently had been overlooked for introductions by a campaign staffer.

"It wasn't their fault. It was the guy in the back room. He doesn't know yet who I am. They forgot," she said.

Mrs. Clinton's speech, when she got there, was a custom fit for Western Pennsylvania, where her husband remains a popular figure. She alluded to that political heyday.

"Sometimes during this campaign, people criticize the 1990s," Mrs. Clinton said. "I've always wondered: what is it they didn't like -- the peace or the prosperity? And how do we get back to those days?"

She said the nation can get back to those days by electing her, and she promised an agenda of job creation, trade protection and changes in the tax code.

"We're going to make sure the tax code is fair again," she said. "I don't think it's right that a Wall Street money manager making $50 million a year pays a lower percentage of his income in taxes than a teacher or a nurse or a truck driver or a worker right here in Pittsburgh making less than $50,000 a year."

She promised tighter trade regulations against foreign imports. "Let's make sure the countries we trade with follow the rules. Let's make sure we enforce stronger rules," Mrs. Clinton said to cheers.

At one juncture, Mrs. Clinton suggested she could create as many as 5 million jobs by steering government research subsidies from "old energy" industries to "clean, renewable sources of electricity."

"We're going to have to say, no, we don't want to be dependent either on foreign oil or on fossil fuels for the next 100 years," she said. "If we do this right, we can create at least 5 million new clean energy jobs over the next 10 years."

With 158 delegates at stake, Pennsylvania remains a do-or-die state for Mrs. Clinton, who trails Mr. Obama in the nationwide delegate count.