President Obama called on a crowd at Temple University's Liacouras Center on Sunday night to elect Democrat Tom Wolf governor Tuesday, casting the election as a choice between failed trickle-down economics and shared prosperity based on a strong middle class.

"The biggest corporations, they don't need another champion. The wealthiest Americans don't need another champion, they're doing just fine," Obama said.

But the hardworking single mother and the first-generation college student need a champion like Wolf, the president said, "somebody who understands that opportunity for all is what America's all about, opportunity for all is what Pennsylvania's all about."

In what may be his last midterm political rally while still in office, Obama sought to stoke voter turnout in the Democratic stronghold of Philadelphia two days before polls open. With his own poll numbers sagging, Obama was not invited to stump for fellow Democrats in some states this year.

But he has campaigned for his party's gubernatorial candidates in Connecticut, Illinois, Maine, and Michigan, as well as in Pennsylvania.

Wolf, a millionaire first-time candidate who ran his family's building-supplies business for more than 25 years, is seeking to unseat Republican Gov. Corbett.

Corbett, a former state attorney general and federal prosecutor, has struggled with low approval ratings throughout his term and is trailing in the polls.

He has been hurt especially by cuts he made in funding for public schools in 2011 to balance the state budget, even as he also lowered business taxes and resisted calls to tax natural gas produced in the state.

Republicans were just as happy as Wolf was to have Obama visit. In recent days, Corbett began running a TV ad portraying Wolf as a clone of a president who is deeply unpopular in most of the state, if not in Philadelphia.

Overall, 32 percent of Pennsylvania voters believe Obama is doing an excellent or good job, according to a Franklin and Marshall College poll last week.

That number was an order of magnitude higher in the city, however, at 51 percent, the poll found.

Obama had jetted in on Air Force One but flew home Sunday night on an official backup plane - the primary aircraft had a "minor mechanical problem" with a wing flap, the White House said in a statement.

The backup jet arrived safely.

On a night when an appearance by Gov. Christie on behalf of Corbett's campaign drew an audience of about 500 in Bucks County, the crowd that came to hear Obama in Temple's basketball arena was estimated at 5,500.

They ran the gamut - young, old, African American, white. Many wore shirts emblazoned with the names of labor unions, several of which are strongly supporting Wolf.

Speaking for 20 minutes, the president praised Wolf's support for raising the minimum wage, ensuring women get equal pay for equal work, expanding access to college, and investing in public schools.

But it all boiled down to one simple message, spelled out in 10-foot high letters held up in the crowd: V-O-T-E.

"Vote! Vote! Vote! Vote!" Obama said. The crowd shouted the word back at him.

Noting that the people in the audience were already convinced of the importance of going to the polls on Tuesday, he implored them also to make phone calls, knock on doors, and "grab the people you know."

Don't give in to fashionable cynicism, the president said.

"Cynicism is sometimes passed off as wisdom. There's nothing wise about it," Obama said. "Cynicism didn't put a man on the moon. Cynicism never started a business, or cured a disease, or fueled a young mind. Cynicism is a choice. And hope is a better choice."