Republican presidential candidate Newt Gingrich has unleashed a new asset on the campaign trail: his wife, Callista.

Coaxed may be more like it. Callista Gingrich, 45, the reserved third wife of the former House speaker with the unmistakable platinum bob, has played a largely non-speaking part at her husband’s side for much of the year. When she has not stood silently by him at campaign events, she has not appeared at all.

That is starting to change. This week, Callista Gingrich went everywhere with her husband over a three-day swing through Iowa. On Friday, the Gingriches will debut a video on Iowa television stations wishing viewers a merry Christmas. And Callista Gingrich has been working on another video in which the French horn player and professional choir singer promotes the value of music education in the public schools.

The second video goes a long way toward revealing how comfortable Gingrich is growing with her role as political wife — a role that she is quick to say she is still getting used to. It announces a platform of sorts, one of three causes that she said she would promote if she is the next first lady.

“It’s important to keep music education in the schools as a means of keeping our cultural identity,” she said in Des Moines during the three-day swing. “It’s a big part of my life. I played the piano and the French horn always, my whole life.”

The other two causes are American history — a “passion” for her and her husband and the subject of her best-selling children’s book, “Sweet Land of Liberty” — and fighting cancer, which claimed her father’s life.

Gingrich, 45, acknowledged that the two videos represent a big step for her toward increasing her role on the campaign trail — a role new to her, since the Gingriches weren’t yet married the last time her husband was a candidate for office. But she has already given a few speeches, notably one to a Republican women’s group in South Carolina, which she said was “fun.” She said her role will continue to grow.

It’s clear that Gingrich is taking the job seriously and even enjoying it, focusing on particular projects such as the videos and the design of the Gingriches’ new campaign bus with a zeal and attention to detail. Showing a reporter a photograph of the bus design, which features the slogan “Rebuilding the America We Love” and an enormous picture of her husband’s head, Gingrich said with a laugh, “There’s the Newtster!”

Gingrich has spent days working with one of the video editors at Gingrich Productions — the Gingriches’ book- and documentary-producing business — tinkering with the music education piece, which is still not quite ready for release, according to the campaign.

She also scrutinized the Christmas video while showing it to a reporter on her iPhone, as if watching it for the first time and eager to know whether others liked it.

“It’s Christmas and it’s Iowa,” she said. “People want to be happy and celebrate the holidays.”

Gingrich also showed great enthusiasm for the couple’s choice of Christmas card this year, which shows the two of them flanking Ellis the Elephant, the patriotic star of her children’s book, which she regularly promotes at book signings sprinkled into the campaign schedule. On that count, too, Gingrich’s mix of enthusiasm and uncertainty came through.

“Do you think it’s in good taste?” she asked. “I thought it was cute, as opposed to the very stuffy cards that go out every year.”

She’s also excited about a new feature that will debut soon on the Gingrich Web page: “Pets With Newt.”

“It was totally Newt’s idea,” she said, laughing.

Gingrich is not quite ready for a formal sit-down interview, a looming milestone for a woman who has yet to explain publicly how she met her husband. The Gingriches began their relationship as an extramarital affair, while Newt Gingrich was speaker of the House — and married to his second wife. Callista Gingrich has been urged by campaign allies to talk more about herself, her music and her other interests, but the question remains whether she will confront the marriage issue head-on.

“We’re asking her to talk about herself,” Gingrich spokesman R.C. Hammond said, who has denied scores of requests for interviews with the candidate’s wife. “When people hear her talk, they find she’s very warm, she’s very interested. They like her.”

Still, that day may come soon. Callista Gingrich is starting to wade into the substance of the campaign. She has been retweeting various Twitter posts recently that criticize her husband’s leading GOP opponent, former Massachusetts governor Mitt Romney. And this week in Iowa, she lashed out at those who have inundated the Iowa airwaves with attack ads — including an independent super PAC supporting Romney — and even managed to squeeze in a plug for her own Midwestern roots.

“People are tired of the negativity,” she said. “But you know, I grew up in the Midwest. I went to college in Iowa. This is my home.”