Updated

Marion, Ohio - With so many swing states to hit in so little time, Vice President Biden mistakenly referred to Ohio as Iowa while attacking Mitt Romney.

"Ladies and gentlemen, this is the guy who's running all the ads here in Iowa saying that he's going to get tough on China," Biden said. Problem was, he was at a high school in Ohio.

Biden, though, clearly knew which state he was in, having only minutes earlier joked he'd been in Ohio cities that sounded like "datin' and marryin" during his three-day swing through the state.

Sharing a conversation he had just wrapped up, Biden told the crowd an "Ohioan said, where are you coming from? And I said, Dayton. And he said, where are you going? I said, Marion. He said, I read in the paper you said you love Ohio. He said, that must be true; you've gone from Dayton Ohio, to Marion, Ohio."

Biden quipped, "I thought -- I'd never thought of that way. I didn't think I was marrying y'all."

The vice president was in rare form in Marion, doling out the Bidenisms with great relish.

He mocked Paul Ryan's comment that the math in the Romney budget was too complicated to convey in a TV interview: "I know the math! The math is the little guy gets crushed and the big guy gets rich!"

He compared Romney's tax proposals to cartoon analogies: "If it looks like a duck, and it walks like a duck, and it quacks like a duck, it's a duck! Man, this is one quackin' duck! This is one quackin' duck!"

As a baby began to cry in the audience, Biden turned in the direction of the tears. "You know what? She just realized what it means, if Romney gets elected," he said.

"Hi, baby. How are you? It's OK, he's not going to get elected. You're going to be OK," the vice president said.