MANCHESTER, N.H. — At Mitt Romney's New Hampshire headquarters, New Jersey Gov. Chris Christie played a time-worn shtick for the cameras, picking up a telephone alongside volunteers who were dialing undecided voters on behalf of the candidate they support.
Mr. Christie actually called Mr. Romney, and the two chatted about an upcoming debate.
"Be yourself," Mr. Christie advised, as he accomplished what he needed to while a dozen reporters watched: He generated positive media attention for a candidate who was elsewhere at the time.
When they can't be in New Hampshire, Iowa and other early-voting states, presidential hopefuls traditionally have sent others in their stead.
But this campaign season, surrogates such as Mr. Christie have been scarce, in large part because the field of candidates was so slow to develop. Mr. Christie, for example, thought of jumping in the race himself until October.
"In the past, you would have had full campaign staffs for all the candidates six to eight months out at least, and some campaigns here are still just starting to put boots on the ground," South Carolina political consultant Luke Byars said.
He said that aside from the candidates' wives and adult children, no stand-ins have spoken in his state, though he expects activity will pick up.
"I still think that's going to happen. It's just a question of time," he said. "It takes resources and staff to make that happen."
In Iowa, Texas Gov. Rick Perry's wife, Anita, has campaigned, and one of Mr. Romney's sons, Josh, filled in for his father this month at the Iowa Republican Party's Ronald Reagan Dinner in Des Moines. But that's nothing compared with 2008, when Mr. Romney's five sons traveled the country in a Winnebago that became known as the "Five Brothers Bus," while Josh Romney drove through all 99 Iowa counties.
New Hampshire has seen a bit more activity beyond politicians' family members. In addition to Mr. Christie making pitches for Mr. Romney, former Pennsylvania Gov. Tom Ridge has campaigned for former Utah Gov. Jon Huntsman Jr. But otherwise traffic has been light.
Tom Rath, a veteran New Hampshire political operative who has advised Mr. Romney's presidential campaigns in 2008 and this year, said surrogates are of limited use in states where voters are accustomed to close encounters with the candidates.
"Frankly, New Hampshire doesn't take kindly to surrogates. We like the candidate. We're spoiled. We see the candidate a lot. We expect to see the candidate. So you have to be very careful," he said. "You can't do them a lot here."
He does consider Mr. Christie the ideal type of surrogate, someone who can bring independent validation of a candidate's message and explain clearly how he came to his endorsement.
That's exactly what Mr. Christie did recently when he attended an evening house party for more than 100 people in Nashua, N.H. He emphasized what he said were Mr. Romney's strengths, criticized President Obama and described why he decided to back Mr. Romney. He finished with a blunt line that drew laughter.
"If there are any of you here tonight who are not yet committed, you better be committed by the time I come back the next time," he said. "I've been real nice to you tonight, and I will not be the next time if you are still on the fence."
In the audience, Paul Laflamme of Nashua said he remained undecided but enjoyed hearing from Mr. Christie.
"I wouldn't make a decision. I wouldn't commit, without meeting the candidate themselves," he said. "However, Gov. Christie is incredibly smart, someone whose opinion I would respect and take into consideration. And hearing what his thought process was was very helpful."