Jay Cost explores the idea that Howard Dean may challenge President Obama from the left in the 2012 Democratic primaries. I agree with him that it's very doubtful, but I have a slightly different take on how such a challenge may affect the race if he does decide to run. Though conventional wisdom holds that a strong primary challenge would be indicative of a fractured coalition that would make it harder for Obama to unite the party in the general election, there's also a way in which such a chellenge could help Obama. In 2008, Obama won on the back of support from independent voters who saw him as post-partisan. In his first year in office, as Obama has governed from the left, he's lost a lot of independent voters. No matter how strong the primary challenge from Dean, ultimately Obama will be able to count on support from liberals in 2012. However if Dean spends months attacking Obama as selling out liberal values, it would be an ideal oppourtunity for Obama to try to portray himself to independents as a centrist within his party ahead of the general election.