The fact that the Mueller probe isn't over -- as Trump lawyers promised him it would be by now -- is likely an issue. Regardless of the reason, it's clear that Trump appears to have shifted from playing nice (or at least his version of nice) to playing, um, less nice. Or, more accurately, from trying to deal with Mueller's investigation to preparing to win the public perception battle in the wake of Mueller's eventual report. Given that Trump has no idea what Mueller will ultimately find, knocking down Mueller's credibility is a necessity. It's not clear to me, however, that Trump is terribly concerned what the general populace cares about as it relates to the Mueller investigation -- or much else.

Source: CNN March 20, 2018 16:52 UTC