Everyone keeps planning to fight the current campaign like they won the last one, and it never works. It is true in warfare, and it is true in politics. Beinart is depending on two things proving true: first, Congressional Republicans have to screw up after the coming win (which is possible), and the president has to move to the center (which isn't likely). And the GOP has very recent experience with getting thrown out of power, and is certain to actively guard against doing stupid things. And there is this. No one is under any illusion that the president is a mildly left of center politician.