Ann Romney says she and her husband, presumptive Republican presidential nominee Mitt Romney, have "nothing" they are hiding in their financial record, but won't be releasing  more tax returns publicly because it will only prompt more attacks.

"We have been very transparent to what's legally required of us,” Ann Romney told NBC's "Rock Center" in an interview scheduled to air Thursday evening. “There's going to be no more tax releases given."

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Mitt Romney has come under intense pressure from Democrats to release more than the two years' worth of returns he has previously disclosed to the public. Senate Majority Leader Harry Reid (D-Nev.) has made an unsubstantiated claim that the Republican had not paid taxes for 10 years. Even Jon Huntsman Sr., a longtime Republican ally of Romney's, has called on the former Massachusetts governor to release more tax returns.

In her interview with NBC, Ann Romney said releasing more returns will only give opponents "more ammunition" but added, "there's nothing we're hiding."

"We have been very transparent to what's legally required of us. But the more we release, the more we get attacked," she said.

Ann Romney's input on the tax returns is just the latest chapter of a story that continues to drag on. It's a distraction the Romney campaign could do without, especially heading toward the late August nominating convention, which is typically a prime opportunity for positive media coverage.