David Frum: "If you work on the assumption that the 2012 GOP nomination contest is a battle between Romney and not-Romney, John Thune's departure helps Romney by removing a plausible candidate who is not Romney."
"If you think Romney is already terminally wounded, then Thune's departure helps the best organized of the not-Romney alternatives: Tim Pawlenty."
"If you think that Republican primary voters are struggling to find a candidate who is 100% conservative but also free from the baggage carried by Sarah Palin and Newt Gingrich, that mission just got a lot harder."