John Opfar sat in the front row of a riser at a Consol Energy facility near Pittsburgh recently just before Mitt Romney took to a makeshift stage. Opfar, 31, is a safety inspector at Bailey Mine in Greene County, the country's largest underground coal mine. He said he likes what he hears from Romney and cannot wait to vote for him: "He talks about what is best for the region and what is best for the country, growing our economy and creating jobs. That's all I need to hear."

By all accounts, this Western Pennsylvania coal miner should be supporting President Obama. But in spite of his working-class roots, Opfar said, "that is not happening."

Two hours later, Romney was across the state in the cavernous warehouse of Stephanie "Sam" Fleetman's Chester County trucking company. Kimberly Wise, Fleetman's executive vice president, said her boss started Mustang Expediting in her parent's attic with a single phone line, and, over the course of three decades, it grew into a company that employs 40. Wise, who has worked at the trucking company for 24 years, has voted for presidential candidates of both parties, but after Romney's visit, she said she is "absolutely" voting for him.

Most of the media coverage of the event focused on whether Romney would pick U.S. Sen. Marco Rubio as his running mate; the Florida freshman had joined Romney for a town-hall meeting in nearby Aston. Less noted was the crowd's enthusiasm and the large number of women present.

Romney spent his time in Pennsylvania plugging holes in his demographic support: In the west, he pitched to working-class Democrats and independents; in the east, he made an economic case to women, younger voters, Rockefeller Republicans, and disenchanted Democrats who voted for Obama in 2008. With Rubio, he reached out not only to Hispanics, but also to tea-party supporters and to college students.

The kind of voters who will swing this election in key battleground states are especially plentiful in the Keystone State, and they are especially dissatisfied with the president's performance.

Pennsylvania tends to be a tease for Republicans in general elections; 1988 was the last time a GOP presidential candidate won the state. Yet, because Pennsylvania is four percentage points more Democratic than Ohio, Florida, or Nevada, a close race here would mean that Obama is losing in those states.

"That is a problem," conceded Dane Strother, a Democratic strategist. "Romney sees opportunity in Pennsylvania, and he is not shy about going for it. ... He knows he might not win Pennsylvania, but playing there is smart. And if he can tighten the margins there, the president is in trouble."

Salena Zito writes for the Pittsburgh Tribune-Review.