After Romney charged that Obama was running a campaign of hate, the first lady walked on stage with her husband hand in hand in Dubuque, Iowa.
He lamented having been away from her for five days, and he drew applause when he said that while he may not be a perfect president, "I do think she is a perfect first lady."
She, in turn, offered a vigorous defense of his character.
"It all boils down to who you are and what you stand for," Mrs. Obama said. "We all know who my husband is, don't we? And we all know what he stands for."
AP Deputy Director of Polling Jennifer Agiesta contributed to this report.
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