Where Mitt Romney can be stiff in public, Ann Romney is warm. Where he is all business, she laughs easily and provides glimpses of a private down-to-earth Mitt who irons his own shirts and does his own laundry.

That, anyway, is the portrait the campaign has been trying to paint through a series of new, intimate interviews with Ann Romney, the one campaign surrogate they believe could dispel a hardening image that her husband is unapproachable and cold.

On Tuesday night, Ann Romney took to the stage to make the argument in her biggest moment yet, a nationally televised address that electrified the Republican National Convention crowd.

She said those struggling in the down economy — particularly women — need help making life a little easier.

“And that is where this boy I met at a high school dance comes in. His name is Mitt Romney and you really should get to know him,” she said.

As a young couple, Ann Romney said, she and Mitt ate tuna and pasta and used an ironing board as a kitchen table. She said he grew from the tall, nervous, funny teen she met at a high school dance to a man with an uncommon knack for creating successful enterprises.

She acknowledged that she and her husband have done better than most. But, she insisted, “as his partner on this amazing journey, I can tell you Mitt Romney was not handed success. He built it.”

As proof of the determination he will bring to fixing the economy, she recounted evidence that only she, as his wife, would know: his devotion as she struggled with potentially deadly health problems, including her 1998 diagnosis of multiple sclerosis.

“I read somewhere that Mitt and I have a ‘storybook marriage.’ Well, in the story books I read, there were never long, long, rainy winter afternoons in a house with five boys screaming at once,” she said. “And those story books never seemed to have chapters called MS or Breast Cancer.”

“A storybook marriage? No, not at all. What Mitt Romney and I have is a real marriage,” she said.

Campaign advisers hope intimate anecdotes from Ann — she recently described how Mitt curled up in bed beside her to comfort her when she was wracked with depression after they learned she had MS — will finally convince the public that he is truly an approachable guy.

But there are pitfalls to Ann Romney’s easy flashes of emotion — her best asset, compared with her occasionally awkward husband.

She has at times come across as peevish in interviews defending her husband. Last month, she accused the Obama campaign of trying to “kill” Mitt with negative campaign ads, and she has appeared befuddled as to why anyone would want to see more of the couple’s tax returns.

And despite a calculated effort to portray Ann Romney as an ordinary, Costco-loving budget hunter, she also is the more public consumer of the couple’s vast wealth than her husband.

Dressage — the expensive equestrian sport that has gotten the Romneys mocked for being out-of-touch with average voters — is Ann’s hobby, not Mitt’s. In May, she gave a television interview while wearing a $990 designer T-shirt.

“She has to show people that she is not aloof and that she isn’t so rich that she can’t identify with them,” said Tony Kimball, a friend of the couple’s from Belmont, Mass., who attended the same church as the Romneys.

Kimball said Ann Romney’s great strength is an empathy that shows in her public speeches.

“Ann doesn’t come across as being terribly wealthy or haughty in person,” he said.

In response to e-mailed questions, Ann Romney said her quiet battle with MS — and later breast cancer — helps her understand ordinary Americans’ struggles.

“We all have our challenges in life, and for me, it has been my health,” she said. “I like to say that we all carry our own bag of rocks. It may not be visible to the rest of the world, but it is there.”

Polls show that Ann Romney has a modestly positive public image, but many voters appear uncertain of her.

An NBC/Wall Street Journal poll in July found that 32 percent of voters felt positively toward the GOP candidate’s wife, while 22 percent held a negative opinion of her. But the remaining 45 percent held either no or neutral opinions of her.

Those numbers significantly lag behind the high ratings that voters have given first lady Michelle Obama.

But campaign advisers think that as the public comes to know more about Romney in the final weeks of the campaign, his wife can play a key role in appealing to women and closing a significant gender gap between Romney and President Obama.

In the lead-up to her moment on the national stage, Ann Romney gave a series of increasingly personal interviews.

She and Mitt invited Fox News host Chris Wallace to watch the couple flip pancakes at the family’s New Hampshire lake home. To CBS News’s Scott Pelley this week, she recounted her heartbreak after suffering a miscarriage in her 40s.

Advisers say voters don’t just like Ann, 63, they like Mitt better when she is by his side. Although her MS means she is easily tired and must take frequent breaks from campaigning, she has appeared at each of the lengthy race’s key moments introducing her husband before important primary night speeches and sitting in his line of sight during debates.

“She is incredible because she is authentic,” said Anita McBride, who served as chief of staff to former first lady Laura Bush. “She presents who she is, and she is not trying to be someone else.”

Philip Rucker contributed to this report.