I think he overestimates his ability to get people to put aside fundamental differences.
Barney Frank on Barack Obama. Frank was specifically criticizing Obama’s choice of Rick Warren to give the invocation for the inaguration ceremonies, but I think his point gets to a more fundamental critique of Obama’s politics.
This sentiment is the core of John McCain’s and Hillary Clinton’s critique of Obama’s position on Iran; it was the reason for Paul Krugman’s and other liberal partisans’ reaction against Obama; and it’s at the heart of the negative response to the Warren invocation. The way this idea keeps cropping up makes me think this will be one of the main memes used to attack Obama going forward. The difference between the first two and this later use of the meme is that the assumption of naiveite has been replaced by an assumption of cold political calculation.