This is an admission of fear from the Romney campaign. You don’t make a risky pick like Paul Ryan if you think the fundamentals favor your candidate. You make a risky pick like Paul Ryan if you think the fundamentals don’t favor your candidate. And, right now, the numbers don’t look good for Romney: Obama leads in the Real Clear Politics average of polls by more than four percentage points — his largest lead since April.
Related point: Two of the top contenders in the Romney campaign’s veepstakes were Ohio’s Rob Portman and Florida’s Marco Rubio. Given that there’s fairly good evidence that vice presidential candidates are worth at least a point or two in their home states, the Romney campaign’s decision to pick Ryan is evidence that they feel they need to change the national dynamic, not just pick off a battleground state.