ROBERT SIEGEL, HOST:
From NPR News, this is ALL THINGS CONSIDERED. I'm Robert Siegel.
MELISSA BLOCK, HOST:
And I'm Melissa Block. Connecticut, Delaware...
SIEGEL: New York, Rhode Island...
BLOCK: And Pennsylvania...
SIEGEL: All those states hold presidential primaries tomorrow.
BLOCK: But, of course, Mitt Romney is not so concerned about the nominating contests anymore. Still, he campaigned today in Pennsylvania. It could be an important swing state in the general election. And it was a chance to audition one potential running mate. NPR's Ari Shapiro is traveling with the Romney campaign.
ARI SHAPIRO, BYLINE: Jane Spresser arrived early for this town hall meeting. She stood in line wearing an American flag T-shirt and a couple of NRA buttons on her jacket. She doesn't love Romney yet.
JANE SPRESSER: He's got to prove himself he's more conservative for me.
SHAPIRO: So why did she schlep all the way out here to wait in line in the damp and cold?
SPRESSER: Rubio is the reason I came today.
SHAPIRO: Florida Senator Marco Rubio, Tea Party favorite and son of Cuban immigrants.
SPRESSER: He's a true conservative. It's in his soul. It's in his blood. He can talk about it without having a note in front of him. I love him.
SHAPIRO: Boy, you just lit up when Rubio's name came up.
(SOUNDBITE OF LAUGHTER)
SPRESSER: Absolutely. He would change the ticket. He would change the ticket. I think he would keep Romney more conservative, and he would bring in some of the Latino vote.
SHAPIRO: This is the first time Romney and Rubio have campaigned together. Before the event, at Romney's first press conference in more than a month, he said the vice presidential gauntlet has barely started.
MITT ROMNEY: We really haven't had a discussion yet of putting together a list or of evaluating various candidates. That's a process.
SHAPIRO: Rubio refused to comment on that process. In front of a cheering crowd, he showed his aptitude at two roles that any vice presidential candidate must play: cheerleader and attack dog.
SENATOR MARCO RUBIO: He's no longer a theory. Barack Obama is a reality. And for millions of Americans today, life is worse than it was three years ago, because he doesn't know what he's doing.
SHAPIRO: Rubio talked about his humble upbringing and turned the story of his unlikely success into an indictment of Democratic proposals.
RUBIO: I don't ever remember my parents saying to me: You know what, if only we took something away from them and they gave it to us, things would be better. I don't ever remember my parents teaching me...
(SOUNDBITE OF APPLAUSE)
SHAPIRO: There was not a lot of public interaction between Romney and Rubio. In a way, Rubio's ease with the audience made Romney's occasional awkwardness stand out even more.
ROMNEY: I know why you're so excited. I heard that the Flyers beat the Penguins last night, 5-1.
(SOUNDBITE OF APPLAUSE)
ROMNEY: That'll do it, huh? That's what did it.
SHAPIRO: Romney said the president has failed to fix the economy. At the same time, he acknowledged that signs are improving.
ROMNEY: I sure hope it keeps getting better. And the president is going to stand up and say he deserves credit for that. No, if it gets better, it's not because of him. It's in spite of him.
SHAPIRO: President Obama won Pennsylvania last time. Romney supporter Larry Snover says the key to flipping the state red this time will be building enthusiasm for Romney in outlying counties like this one to match the enthusiasm for the current president in Pennsylvania's urban centers.
LARRY SNOVER: Depends on whether people in Philadelphia, Pittsburgh, Scranton and the inner cities, who - I'm sorry - don't many times have any skin in the game, so to speak, whether they come out and vote in volume.
SHAPIRO: Snover was talking about poor people receiving government benefits. Yet even here outside of Philadelphia, Romney has some work to do.
PHYLLIS MEYERS: He says a lot, but he doesn't say anything.
SHAPIRO: Phyllis Meyers describes herself as a lifelong Republican who voted for Barack Obama in 2008 and doesn't know who she'll vote for this time. She came to see whether Romney could win her over.
MEYERS: He's a crowd pleaser, and he's handsome. And he has a nice manner about him. That doesn't do it for me.
SHAPIRO: Romney may not have won points with her when he joked at the beginning of this town hall meeting: Now you get to ask questions, and we get to dodge with our answers. Ari Shapiro, NPR News, Chester Township, Pennsylvania.