As we reflect on Kennedy's legacy, I'm struck by how key his January 2008 endorsement of Barack Obama now appears. His announcement came reasonably early (before Super Tuesday), and, as Marc Ambinder pointed out, "allow[ed] him to separate the politics of the Clintons from the politics of Democrats before the Clinton administration." Moreover, his pick helped both to mainstream Obama's appeal and confer the blessing of a very respected wing of the Democratic Party.