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  • ON THE BALLOT photo | Katy Perry

Credit: John Gurzinski/Getty

Published: Thursday Oct 25, 2012 | 05:00 PM EDT

ON THE BALLOT

Rock the vote! Katy Perry – who celebrates her 28th birthday today – gets the crowd energized while performing at a campaign rally for President Barack Obama Wednesday night in Las Vegas. "The PRESIDENT gave grandma and I unforgettable sour outs & now I am officially 28!" she Tweeted. "Best. birthday. ever."