The candidates are not only scrutinizing each other’s past speeches and issue positions but also their recent appearances. After Biden’s blistering critique of the GOP ticket in Iowa, Ryan studied a transcript of the event. Biden’s preparation also has included reviewing video of Ryan interviews and speeches.

One Romney aide said that the presidential debate did little to change the substance of Ryan’s debate preparations “except that he needs to be even more prepared for a really aggressive tone and tenor from the vice president.”…

Some Democrats dismiss the notion that the stakes are raised for Biden — and counter that the onus is on Ryan not only to defend Romney, but also to prove that he himself is ready for prime time.

“I think the pressure in my book is on Paul Ryan, because he’s got to demonstrate that he has what it takes to be president of the United States,” said Democratic strategist Doug Thornell. “We know he can work a calculator and a budget — not that the numbers add up — but there’s a lot of other qualities that he hasn’t demonstrated.”