The Scott Walker recall is already historic. Last month, organizers submitted signatures from over a million Wisconsinites, the largest portion of an electorate to ever petition for recall of a United States governor. The total – nearly double the number required – means near-certain certification by the state’s election board of what will be the third gubernatorial recall in American history. This week’s $700,000 pro-Walker ad buy by the Koch brothers’ Americans for Prosperity was the latest confirmation that the Walker recall will be a marquee race. But what kind of race will Walker’s opponents seek: a battle of competing centrist appeals, like the fall presidential election, or something very different?