Ann Romney, resplendent in red, vouched for Mitt Romney's heart. Chris Christie vouched for the Republican presidential candidate's spine.

The potential future first lady and the blunt-talking New Jersey governor capped the second day of the Republican National Convention with a pair of much-anticipated speeches seemingly designed to counter two of Mitt Romney's perceived weaknesses. Ann tackled his difficulty connecting to voters, especially women. Christie confronted head-on Romney's flexibility on issues the party's base regards as non-negotiable.

"I want to talk to you tonight not about politics and not about party," said Ann Romney, long her husband's best asset on the campaign trail. "Tonight I want to talk to you about love."

"Tonight, we choose respect over love," Christie said, describing how his late mother "told me there would be times in your life when you have to choose between being loved and being respected."

Ann Romney urged the delegates packed into a Tampa sports arena to "to think tonight about the love we all share for those Americans, our brothers and sisters, who are going through difficult times, whose days are never easy, nights are always long, and whose work never seems done." She paid special tribute to women, who in tough economic times always seem to be "sighing a little bit more than the men."

Mitt Romney, who leads Obama among male voters but trails among women, is "warm and loving and patient," a leader defined by "love of one's fellow man," she said. "Mitt doesn't like to talk about how he has helped others because he sees it as a privilege, not a political talking point," she said.

[Slideshow: Ann Romney fashion]

"This man will not fail. This man will not let us down. This man will lift up America!" said Ann, who first met Mitt Romney at a dance when they were teenagers. "You can trust Mitt. He loves America. He will take us to a better place, just as he took me home safely from that dance."

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She also allowed herself a dig at Obama "I can tell you Mitt Romney was not handed success. He built it." (Republicans have built a campaign theme out of the president's contention that entrepreneurs have government to thank for the investments in infrastructure and education, having taken his message to business owners that "you didn't built that" out of context). But it was one mild shot in a speech devoted to a portrait of Mitt Romney as a warm, compassionate life partner.

But if she sang in the register of compassion, Christie roared a political battle cry, promising that the former Massachusetts governor will tell "the hard truth" about America's ills and make "tough choices" like reining in entitlement spending—notably on programs for the elderly.

"Our problems are big and the solutions will not be painless. We all must share in the sacrifice. Any leader that tells us differently is simply not telling the truth," said Christie, whose speech often focused so heavily on his record in New Jersey that at times it was possible to forget that he was neither candidate nor running mate.

"We have a nominee who will tell us the truth and who will lead with conviction. And now he has a running mate who will do the same," he said.

Christie imagined the judgment of history and the fate of his children and grandchildren and declared "I want them to live in a second American Century." ("I." Not "Mitt Romney and I." And definitely not just "Mitt Romney.")

"I won't be part of the generation that fails that test and neither will you," Christie said. "It's now time to stand up. Let's stand up. Everybody stand up. Because there's no time left to waste."

"If you're willing to stand up with me for America's future, I will stand up with you," he thundered. "If you're willing to fight with me for Mitt Romney, I will fight with you."

"If you're willing to hear the truth about the hard road ahead, and the rewards for America that truth will bear, I'm here to begin with you this new era of truth-telling," he said.

Romney drew fire during the Republican primaries for his changing stances on a range of issues, and then again after a top adviser said the candidate would "Etch-a-Sketch" primary positions designed to win over core conservatives in favor of courting middle-of-the-road voters who decide the general election.