A couple of very interesting reads:
John Avlon, author of "Independent Nation..." and chief speechwriter/deputy policy director of Rudy Giuliani's Presidential campaign, says Senator Obama's campaign - and secret of his success - has been Obama's constant centrism. He offers good examples of Obama's bipartisanship in the US Senate, and also facets of Obama's policies that are not the usual far-left litany (e.g. Obama wants to expand the military!)
Kirk Dillard, an Illinois State Senator, has praised Barack Obama and has been featured in an Obama ad... But he has faced a lot of opposition from his party - the GOP! Here's a story about Dillard's struggles on Politico.