...the Constitution...
He has a poor grasp of federalism and the 10th Amendment.
He's doing a good job and has from the first day in office, but sometimes he steps in it.
^^^^The truth.
I've noted that he keeps Bill Barr close at hand in many of these briefs. That tells me he realizes he isn't an expert on the Constitution.
He's a very smart man. Knows his capabilities and limitations. Relies on others he can trust to cover his gaps.