Artur Davis stood onstage at the Democratic convention in 2008 and provided the official second for President Obama's nomination.
On Tuesday, he said he screwed up.
"The last time I spoke at a convention it turned out I was in the wrong place," the former Democratic congressman from Alabama told Republican delegates. "So Tampa, my fellow Republicans, thank you for welcoming me where I belong."
The Democratic party? "You know, the Democrats used to have a night when they presented a night of their presidential legends. Folks, if they do it in Charlotte, the theme song should be, 'Now youre just somebody that I used to know.'"
Davis threw his support behind Mitt Romney, saying he doesn't confuse the presidency with celebrity or loftiness with leadership.
Later, he struck again at Obama, suggesting that many Americans were impressed with the words and staging of his 2008 convention speech in a Denver football stadium: "Maybe we should have known that night in Denver that things that began with Styrofoam Greek columns and artificial smoke typically don't end well," he said. "Maybe the Hollywood stars and the glamour blinded us a little."
Davis asked Democrats and independents whose minds are open to argument to watch Democrats at their convention next week and, if they're unimpressed, to vote for Romney.
Ahead of his speech, 14 members of the Congressional Black Caucus penned an angry letter to Davis, saying that his speech Tuesday was the result of a nakedly personal and political calculation or simmering anguish after failing to win the Democratic nomination for Alabama governor in 2010.