Constitutions,conventions and power

Subject: Constitutions, conventions and power.

Watching the American TV Channel, C-SPAN I was struck by the fluency of the Academic speakers in their role of describing the apparent dilemma of President Trump and the American notion of the Separation of Powers in their constitution.
We are bombarded with everyday Twitter bombast from Mr Trump and we wonder at the danger, to us all as he rampages on many topics which we had thought protected by the Constitution. His populist diatribe seems to get to the root of a decision making process which pray on fear. Fear of the immigrant, fear of dissident cultures, fear of outside interference in terms of economics, of loosing face in a world which is itself more at odds with itself. 
Is Trump authoritarian. Not in terms of the sort of authoritarianism exhibited by Mr Putin or Xi Jinping of China. He is limited by Congress in his funding and whilst his bombast scares many liberal thinking people, his ability to set in motion many of his more scary ideas is limited. 
Russian and Chinese leaders are not constrained from carrying out what ever they dean necessary and even a British Prime Minister, with a majority is only limited by convention and we see, in the most recent addition, a willingness to throw out even tried and trusted Convention which has  placed parliament in a difficult position, having no written framework like a binding Constitution to limit him.
The frustration in America is that two ideologically opposed views as to what is good for the people and the nation sit at opposite ends of a corridor and without cooperation, nothing gets done. In Britain once an election is decided then for 5 years the party and more prosaically  the man or woman who that party elects as leader has untrammelled power to do much as they please.
The academics on C-SPAN were mostly law professors majoring in constitutional law and I was fascinated by their collective assurance that the worst impulses could be contained. Contrast this with the panic amongst the MPs in the Mother of Parliaments who seem, faced with an unintended impasse where there are no rules, only a series of conventions and that if Convention is trashed, they are powerless to do much about it.