CNN has the background, "Axelrod launches attack on Romney's home turf."
And see Ed Morrissey, "Video: Famous Chicago political organizer … outorganized?":
This sums up perfectly the first month of the general election campaign. The team with the community-organizing experience thought they could secretly arrange a rally in their opponent’s home state to attack his record as governor, led by the chief organizing genius of the campaign. David Axelrod got a large, unpleasant lesson in Chapter One of This Ain’t 2008 Any More...RTWT.