PHILADELPHIA -- Anthony Paradiso had attended his last political event nearly a half century ago. But there he was, in line three hours early for a glimpse of Michelle Obama.

“She’s a motivator,” said Paradiso, who went to the rally just two days after he’d been discharged from a hospital after surgery. His last event: a Hubert Humphrey rally in 1968.

It’s that kind of appeal that President Barack Obama’s re-election campaign loves, hoping the popular political spouse can rekindle some of the 2008 spark among Democrats and independents for a contest that’s looking more difficult by the day.

“This journey is going to be long and it is going to be hard,” the first lady said, delivering a feisty stump speech to more than 1,000 supporters and campaign volunteers who were jammed into the National Constitution Center. “But just remember, that’s how change always happens in this country. And if we keep showing up, if we keep fighting the good fight, then eventually we get there.”

Obama has been politically active on her husband’s behalf for more than a year, raising money at nearly 60 fundraisers and conducting conference calls with key groups of supporters, including women and African-Americans. She’s also a pop culture phenom, making a guest appearance on the Nickelodeon TV show "iCarly" to thank military families for their service and engaging in a tug-of-war with comedian Jimmy Fallon to promote her “Let’s Move” initiative.

But as the campaign heats up, she’ll be deployed to headline more large rallies like the ones last week in Pennsylvania and Virginia.

“Next to the president himself, and maybe including the president, she’s our most in-demand surrogate,” campaign adviser David Axelrod said. “She is both tremendously popular and very effective on the stump, because she speaks in a heartfelt way about (the president), and what motivates him, the things that he’s done and the things that he wants to do.”

The campaign will have to compete with her "No. 1 priority" – the couple’s two daughters – but as much time as she will give, Axelrod said, the campaign will want her out there.

Polls consistently find Michelle Obama at or near the top of the list of the most popular political figures in the country. She outscores her husband by double digits: Her favorability rating was 63 percent in an April poll by the Marist College Institute for Public Opinion, while President Barack Obama was at 50 percent.

“We believe in him, but her support really seals it,” said Gloria Pelzer, a retired Bucks County schoolteacher who volunteered for Obama in 2008 and plans to sign up again. “She’s a dynamo.”

First ladies are often more popular than their husbands, perhaps because of the non-combative nature of the position.

Laura Bush campaigned for congressional candidates across the country for former President George W. Bush in 2006, a time when his popularity was flagging. First lady Hillary Clinton campaigned extensively in 1998, preferred by fellow Democrats at a time when her husband faced impeachment.

Political strategists note that a popular spouse often can humanize a candidate, an important factor for President Obama and presumptive Republican nominee Mitt Romney, both of whom can appear aloof.