"Since when does the United States President have this kind of authority? There is literally nothing in the Constitution that enables anything even close to this sort of thing. The President is tasked with executing the laws passed by the Congress, not writing them himself, and there is nothing in Article One, Section Eight of the Constitution enabling Congress to mandate anything like this either"
In summary, if the mandate flies then the Constitution is toast, If it doesn't then the Biden Pretendency is toast.
Given the growing number of States that are queuing up to take these measures to the courts, it's not hard to see which way the wind may be blowing.