Former first lady Nancy Reagan also issued a statement Monday thanking Obama for lifting the ban.

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Former First Lady Nancy Reagan, standing in for her Alzheimer's-stricken husband, borrowed a riff from her famous anti-drug crusade.

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He said Reagan led "with great grace, " and he expressed his condolences to Reagan's widow, former first lady Nancy Reagan.

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Fred Thompson, and former first lady Nancy Reagan were also in attendance.

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With former First Lady Nancy Reagan looking on, Paul disagreed with President Reagan's choice of Sandra Day O'Connor as a Supreme Court justice, while Huckabee and McCain declined to say whether they would have tapped her for a spot on the high court.

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And in particular, I want to thank our special guest here today, Nancy Reagan, our former First Lady, who redefined that role in her time at the White House -- and who has, in the many years since, taken on a new role, as an advocate on behalf of treatments that hold the promise of improving and saving lives.

WHITEHOUSE: THE WHITE HOUSE