Support for the President seems very solidly around 35% to 37% (outliers not withstanding), and I doubt there is much he could do to alienate his core supporters (I think he was right about shooting someone and not losing much base support). That's obviously not enough to get reelected though, and his current level of support probably has the GOP up for re-election next year nervous. I doubt continuing to play games with tweets and with daily press briefings will help his approval ratings, and that's largely what he's doing IMO.
If he doesn't realize he needs to start acting Presidential, that his words as President have real import, and that serving as President is more than playing a character, I believe his Presidency is doomed to failure and will continue to wallow in defiance and settling of petty differences. Treating the American public with respect by actually answering reasonable questions (beyond just Fox News) would be a good start IMO. Sadly, I don't see it happening. Just another missed opportunity and self-inflicted wound for this Administration.