MANCHESTER, N.H. — In previous presidential races, candidates usually would send stand-ins when they couldn't make it to New Hampshire, Iowa and other early voting states.

But in the crowded 2012 GOP contest, those surrogates have been scarce, largely because the field of candidates was slow to develop.

New Hampshire has seen a bit more activity than Iowa and South Carolina, with former Pennsylvania Gov. Tom Ridge campaigning for Jon Huntsman and New Jersey Gov. Chris Christie filling in for Mitt Romney.

Tom Rath, a Romney adviser, says surrogates are of limited use in states like New Hampshire, where voters are accustomed to close encounters with the candidates.