I think deep in his heart he loathes the thought of Hillary coming in and tampering with his legacy. He will go through the motions of supporting her, but his heart will not be in it. And he will be smiling inwardly if she loses!
And a Republican wouldn't "tamper" with it even more?
Yes but Obama hates the Clintons! He might rather see a Republican president. At least then his legacy would be all his. If Hillary comes in she might get credit for implementing the liberal agenda better than he did. A Republican won't get any credit from the mainstream media. It will be "Obama was a saint, now we have a mean right wing kook!"