In Party of One, the Boston Globe explains that, “Far from the cause of Lieberman’s difficulty, Iraq is a catalyst that has triggered a blow-up between the senator and his party that has been brewing for years.” A lot is being said about Senator Lieberman’s primary (though I think Colbert may have said it best), but this three-page article in the Globe’s Ideas section does a good job of providing some historical context. If you’re not up to date on this story, I recommend starting with this article.