Low-Key Democrat Leads High-Stakes Senate Race

"But also I was influenced by the idea that sometimes you've got to stop what's going on, and you may be the only person that can do that," he said.

By midsummer of this year, Santorum had raised substantially more money than Casey -- $17.2 million to $10.8 million -- much of it going toward advertising that has portrayed Casey as a ladder climber, a candidate with only the vaguest positions, and, in an attempt to convey that he is not the same Casey as his father, "Bobby."

"What you heard from Mr. Casey is what you hear all the time. No specifics," Santorum said when the two debated on "Meet the Press" in early September. Casey, however, who was anything but docile in the debate -- sometimes interrupting Santorum, sometimes correcting him, sometimes mocking him -- was well ahead in the polls at that point.

He has been leading in the polls since spring. The only blip in a steady stream of successes came in a poll a few weeks ago, which showed that unfavorable reactions to him had risen from 13 percent in May to 22 percent in September as Santorum ramped up his attacks. "Santorum, at the moment, is defining Casey better than Casey is defining himself," said Madonna, the pollster.

What the poll also showed, however, is that the race is far less about Casey than about Santorum. Nearly 30 percent of likely Casey voters said they support him mainly because he's not Santorum -- "a pretty high percentage," Madonna said. And as Santorum's unfavorable rating has climbed from 26 percent when Casey entered the race to 37 percent in September, the Casey campaign has seemed content to remain low key, letting Casey be defined less by who he is than by who he is not.

As McGrath said, when asked who her brother is: "He's not a polarizing figure."

Who is he, though?

At a second campaign stop in Reading, this one with union workers at a small hotel, Kathy Quimby watched Casey come in.

"Wasn't his father in politics?" she asked, trying to figure out where she had heard Casey's name.

Quimby, who works at the hotel, watched as the candidate went around the room, shaking hands and speaking in an even voice about what is wrong and right in the country.

Chalk up another vote against Santorum: "He seems like a nice guy," she said.