For me, the issue is not so much whether it is legal and/or constitutional or not. Rather, it is that this president and his followers, including those he appoints to represent him in official capacity, believe they have the power to do whatever he wants them to do.
Clearly, Mr. Trump sees himself as the CEO of the large international company called the United States Government and, as the head, he expects every one of his wishes to be implemented and followed immediately. So he refuses to tell us where his money is, who his “friends” are, what relationships he has with foreign countries, and he just starts to build his wall, threaten states (like California and their higher environmental standards) and cities (like Chicago with its very public murder rate) with federal intervention, demanding that his spokesmen rely on ‘alternative facts’ when they communicate with the people.
Almost none of his appointees know how government at any level runs and they all probably believe him when he told us that he was “the only one” who could solve these problems.
God help us.