Republican candidates: This holiday season, the wives are working overtime.

In a new ad touting her husband’s Christian values, Anita Perry – in eye-popping royal blue – tries to make the case that Rick Perry’s family and American roots are as deep as those of the giant tree towering behind her.

“When Rick’s tour of duty as a captain in the Air Force ended, he returned home to farm with his dad and asked me to marry him,” she says of her high-school sweetheart.

It’s one of several political ads making the rounds this week featuring Republican candidates’ wives. And spouses have hit the campaign trail too, chatting with voters as they munch on pizza or practice target shooting.

On Wednesday Mitt Romney tweeted: “My wife Ann is a remarkable woman – she has been my biggest champion....” and he included a link to a new ad full of black-and-white photos from their family life. In it, Ann Romney says in part: “You can never predict what kind of tough decisions are going to come in front of a president’s desk. But ... if you really want to know how a person will operate, look at how they’ve lived their life.”

Newt Gingrich and his wife (she’s decked out in royal blue, too) put out a happy holidays ad Dec. 19, complete with soft music and images of candles aglow. “Is there anything more inspiring than American towns and neighborhoods brightly lit for the holidays?” says the perfectly quaffed Callista Gingrich. Then candidate Gingrich says that it’s a reminder “of the fire of freedom that burns bright in the America we love.”

“Campaigns are about policy and character, and the family comes in for the character part,” says Julian Zelizer, a professor of history and public affairs at Princeton University in New Jersey. “It is a softer side of the campaign, but one that can have a bite in some cases.”

An earlier Romney ad featuring his marriage of 42 years, for instance, is designed to contrast him with Mr. Gingrich, for whom Callista is the third wife – a relationship that started as an extramarital affair.

While Gingrich may be hoping to project more confidence among voters by showing his wife’s support, it may instead “highlight one of his vulnerabilities,” says Jennifer Lawless, a government professor at American University in Washington, D.C.

It’s not surprising, Professor Lawless says, that if one candidate puts out an ad featuring his wife, others hasten to follow. In a Republican primary, it might matter to voters “if the candidates are emphasizing traditional family values and traditional conceptions of family structures,” she says.

Wives can play a role in a candidate’s ability to continue a campaign. Gloria Cain helped her husband hold onto many women voters when she defended him against allegations of sexual harassment. But she also may have influenced his decision to step out of the campaign after facing accusations of an affair.

Jon Huntsman’s wife, Mary Kaye, has been campaigning for her husband in New Hampshire recently, and she’s been enthusiastic from the start, The Boston Globe reports.

Messages from male candidates’ wives are sometimes more persuasive to female voters. Case in point: Gail Bourque, an independent in New Hampshire, told NHPR radio that she was won over to Ron Paul’s campaign because of a recent mailing from his wife, Carol. “If you want to get the woman vote, have your wife send out the message,” Ms. Borque said.

And don’t forget the husband on the campaign trail: Michele Bachmann’s husband, Marcus, stirred up controversy earlier in the race because of his work counseling about homosexuality.

But lately he’s been touring Iowa with a group of conservative Christians to promote his wife. He stopped off recently in Evansdale for a photo opp at a shooting range and touted US Representative Bachmann’s belief in Americans’ right to bear arms, according to the Cedar Valley news website wcfcourier.com.

But in the general election, while spouses can be helpful campaigners, they’re not usually the reason people cast their vote, Lawless says.