I think you folks are talking past each other. The constitution requires faithful fulfillment of the duties of office, so because of that requirement, presidents swear oaths of duty. Lying under oath is a crime (not delineated in the constitution) and a violation of the faithful fulfillment of duties, which means that he is violating the terms of presidency set out in the constitution (also not a crime, but impeachable).
I think you folks are talking past each other. The constitution requires faithful fulfillment of the duties of office, so because of that requirement, presidents swear oaths of duty. Lying under oath is a crime (not delineated in the constitution) and a violation of the faithful fulfillment of duties, which means that he is violating the terms of presidency set out in the constitution (also not a crime, but impeachable).
But you’d have to prove beyond reasonable doubt that he intended not to uphold the oath of office when he made it.
Not to impeach him, just to successfully charge him with purgery.