He’s acting as if he is, as if there are no other branches of government. I think he is in pre-dictator mode, much like Hitler in 1933.
OTOH, when corrupt republics are in their final days, a tyrant may emerge. The powers of tyrants have no time limit. Tyrants are outlaws hostile to republican freedom. Tyrants assume, grasp, and otherwise illegally seize powers that dont belong to them. They either destroy republican institutions outright, or like Obama, they squeeze the neck of institutions like congress that stand in their way. In time, once free institutions are compromised and become docile, subservient rubber stamps to the will of the tyrant.
We technically have a constitution, yet for practical purposes we don't, not because of a dictator, but because congress has unconstitutionally relinquished power which has subsequently swirled into the hands of an appreciative tyrant, Obama.