In years past, Microsoft has dubbed its preview releases as release candidates or betas.

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Federal campaign law does not require candidates to release tax returns, but it does require candidates to file annual financial disclosure paperwork, which Romney has done.

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Unlike many presidential candidates, he refuses to release his tax returns.

ECONOMIST: Mitt Romney

Romney's tax returns previously arose as an issue in January, when Democrats, along with fellow Republican presidential candidates, pressured Romney's campaign to release the documents.

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Hassan did not speak on the company's conference call, and he did not point to any promising candidates in its drug pipeline in the press release.

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However, he had initially refused to release the returns, saying the financial disclosure reports that all federal candidates must provide should be enough.

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