PHILADELPHIA (AP) — The fight to win Pennsylvania brought former President Bill Clinton to the battleground state on Monday, as he campaigned in the state’s biggest cities to help Democrats try to fend off an aggressive, last-ditch attempt by Republicans to capture its prized 20 electoral votes.

In near-freezing temperatures in downtown Pittsburgh, Clinton played up President Barack Obama’s efforts to save the American auto industry and his work with governors to respond to last week’s destructive storm. In Philadelphia, he told a raucous crowd at the University of Pennsylvania’s Palestra sports arena “to vote for your hopes and not for your fears.”

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Clinton, perhaps Obama’s most powerful and popular advocate, came as Republican presidential nominee Mitt Romney and conservative groups make an expensive, 11th-hour plunge into Pennsylvania to try to capture a key stepping stone for Democrats to the White House.

No Democrat has won the presidency without Pennsylvania in 64 years. Pennsylvanians also will decide a U.S. Senate race in Tuesday’s election that could help determine control of the chamber.

Underscoring the state’s importance, Romney announced an Election Day stop in Pittsburgh. Clinton was to end the trip Monday night with a rally in Scranton, the hometown of Vice President Joe Biden, U.S. Sen. Bob Casey and Democratic attorney general nominee Kathleen Kane.

Meanwhile, Pennsylvania’s other U.S. senator, Republican Pat Toomey, led GOP Senate nominee Tom Smith and attorney general nominee David Freed in a cross-state hopscotch as they greeted Republican gatherings in every TV market. They were to end the night with a rally in Pittsburgh.

Clinton was greeted by chanting, cheering college students who packed the Palestra.

“The America I have been fighting for since I was a boy is on the line,” Clinton told them. “The future of America in the 21st century is on the line. … I want you to wake up in the morning with a smile on your face, a song in your heart and a spring in your step, because America is coming back.”

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In Pittsburgh, a hoarse Clinton gave a high-energy pitch in the 38-degree chill to a crowd of hundreds, questioning Romney’s opposition to support for the auto industry and praising Obama for bringing troops home from Iraq.

“I want the candidate who decided to save the American auto industry,” Clinton said. Pennsylvania has about 40,000 jobs tied to carmaking, according to an industry group.

In a hotel gathering in Camp Hill, a Harrisburg suburb, Toomey criticized Obama for unemployment being higher than it was when he took office in 2009, and pitched Romney as the right candidate to address the nation’s “economic misery.”

“He is going to hit this ground running the day after the election. He’s not going to wait until he’s sworn in and he is going to start to implement as soon as he can, a plan that is going to put us back on path,” Toomey said. “We’ve got the right man for this moment in Mitt Romney, and he’s going to start with real change on Day 1.”

Elsewhere, former New York City Mayor Rudy Giuliani led a team of ex-Republican officeholders and actor Jon Voight to stump for Romney in Pennsylvania. In Conshohocken, about 150 supporters listened enthusiastically, with life-sized cutouts of Romney and running mate Paul Ryan serving as a backdrop as Giuliani criticized Obama for what he called a lack of leadership.

Polls are open Tuesday, from 7 a.m. until 8 p.m., as the political parties and other groups crank up huge get-out-the-vote efforts and deploy poll watchers and lawyers to address voting complaints or to watch for dirty tricks or perceived irregularities. Philadelphia District Attorney Seth Williams said his office will have mobile units available to be dispatched to any polling place if there are reports of voter intimidation, fraud or harassment.

The last-minute blitz of presidential campaign ads — mostly attacking Obama — has added to voters’ weariness. But Ian Smart wasn’t complaining as he waited near the back of the line that snaked around the block to the Palestra.

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“This has been a long and frustrating few months, but the momentum is with us,” the Drexel University business major said. “I feel very confident about the outcome tomorrow. I’m fired up.”