You sometimes hear political hands say that a campaign's most valuable commodity is the candidate's time.
So why would Mitt Romney, who needs to court Pennsylvania's working class Democrats and suburban independents make a campaign appearance in today in the heart of Obama country, visiting a charter school in West Philadelphia?
As might be expected, neighbors were cool to hostile, and Obama folks showed up in force, including Mayor Nutter and District Attorney Seth Williams. The pair set up a podium outside the school and condemned Romney's record on education.
What does Mitt get out of something like this?
Well, for one thing, he's gets coverage in the huge Philadelphia media market, which reaches many of those swing voters he needs.
And there were some nice "optics," including Romney being serenaded by black school kids at the Bluford Charter School, named for the nation's first African-American astronaut, a native Philadelphian.
When Romney smiled at those kids and sat down for a roundtable with African-American teachers and administrators, it wasn't because he expects to get votes in West Philadelphia's fourth ward, where Democrats outnumber Republicans 20 to one.
The target, really, was white voters.
It was a signal to white liberal and moderate voters that he cares about urban issues and is not indifferent to the poor. The idea was to give permission to white moderates to vote for him if they're dissatisfied with the president.
I watched the "roundtable discussion" on education, which was hosted by record mogul Kenny Gamble, whose Universal Companies runs Bluford and four other charter schools.
Romney embraced education policy with a Republican bent, favoring more choice, more digital learning, and more state control over education funds.
And he spoke positively of a provision in a Massachusetts law for troubled schools, "a provision that said if a school is consistently failing and the state takes it over, they can remove any provision in the union contract which they think is interfering with the education of the children."
A couple of teachers pushed back a bit when Romney suggested that smaller class size wasn't a critical factor in better performance.
"I can't think of any teacher in the whole time I've been teaching, over ten years, who would say that they would love more students," said Steven Morris, a teacher at the school.
Besides the planned protests and mayoral news conference outside, there were some spontaneous outbursts, the most entertaining from Darnel Tanksley, who lives across the street from the school.
He stood on his porch, waving a poster and yelling at the Romney bus and campaign staff.
"Stop Republican Hillbilly logic! Hillbilly Republican logic will ruin America!" he shouted repeatedly.
When I spoke to him, Tanksley said he has nothing against country folk, "I like Elly May Clampett," he said. "Huey Long was a hero to many Democrats. Charlie Pride has his place in American history. But hillbilly Republican logic will ruin America."
Not exactly sure I get it. But he was passionate, and I have no doubt that Romney's staff, if not the candidate himself, heard him.
But I noticed there was one elderly African-American man who sat in the Romney roundtable and later mingled among the protestors.
He's David Fattah, a board member of the charter school and father of Philadelphia Democratic Congressman Chaka Fattah. He explained why he sat down with Mitt Romney.
"The children are above politics. They're above how we feel about personalities," Fattah said. "If (Romney) hadn't come out today, people wouldn't be standing in front of this school. I'm extremely proud that our children get to see important people, people running for president, and it let's them know they can run for president too."
When the Romney bus and protestors left, classes resumed at Bluford Charter.