TAMPA, Fla. - Before Ann Romney walked out onstage to deliver a critical speech to the Republican National Convention on Tuesday night, South Carolina Gov. Nikki Haley described her as Mitt Romney's "silver bullet."

In a speech carried by the major networks and cable stations, Romney tried to use that bullet to end the Democrats' portrayal of her husband as a dispassionate businessman who is anti-woman and anti-middle class.

Instead, she portrayed him as women's strongest advocate. "It's the moms who always have to work a little harder to make everything right," she said. "It's the moms of this nation -- single, married, widowed -- who really hold this country together."

In an effort to humanize her husband, she talked about the early days of their marriage in a basement apartment, eating pasta and tuna fish. "I read somewhere that Mitt and I have a storybook marriage," she said. "Well, in the storybooks I read, there were never long, long rainy afternoons in a house with five boys screaming at once."

She said Romney "was not handed success. He built it."

She said her husband has been generous with that success. "Mitt doesn't like to talk about how he has helped others, because he sees it as a privilege, not as a political talking point."

Debra Forrest, an Arizona delegate, called the speech "powerful." Ann Romney, she said, "related so well to the women of America."

Most of all, her speech aimed for the critical undecided female voter.

President Obama leads Romney among female voters by about 8 points, according to a recent Gallup poll.

"I love you women," Romney said, describing how she can relate to the responsibilities of mothers and wives. "You are the best of America, you are the hope of America. There wouldn't be an America without you. Tonight, we sing your praises."

Romney said her husband would help women out of the hardships they now experience in the struggling economy. "This is the man America needs," she said.

"No one will work harder, no one will care more and no one will move heaven and earth like Mitt Romney to make this country a better place to live," she said.

Ann Romney, wearing a bright red dress and surrounded by a giant backdrop of family photos, received by far the most enthusiastic reception of the convention so far.

"I can't wait to see what we are all going to do together," she told a cheering crowd. "This is going to be so exciting!"

Delegates said Ann Romney's speech was needed to show the human side of her husband, to counter the Democrats' caricature of him.

"The character from Monopoly," New York delegate Jeffrey Oppenheim said. "The guy with the monocle and the top hat, the indifferent capitalist."

It's an unfair characterization, Oppenheim said, "but nonetheless, it's one that has to be refuted."

Toward the end of her speech, Ann Romney made a "solemn commitment":

"This man will not fail. This man will not let us down. This man will lift up America."