Important aside: Americans owe no loyalty to the president of the United States. While we may owe loyalty to the office of the president, and certainly owe loyalty to our constitution, any given person holding the office is just an employee. Our employee.
Since the start of the United States, those individuals who have occupied the office of the presidency have sought, and succeeded, in enlarging upon the power of the office. Both pragmatists and egoists, these actions should not be heralded, but scorned, because it was their job to carry out the duties of their office, not to increase their personal power in that office.
The end result of these actions has been indeed to increase the power of the presidency. But what is not seen is that by doing so, they *decrease* the level of loyalty owed the office by the citizenry.
Were the president to declare himself dictator, he would have immense power, but no citizen would owe him or his office any loyalty whatsoever. Yet despite his trampling of the constitution, we would still remember, honor, and retain our loyalty to it and its principles.
So when asked to whom our loyalties lie, father or king?, or king or Pope?, perhaps the best response would be “faith and constitution”.
The loyalty to the constitution is not absolute either. When it speaks to how the elections are held, taxes levied, public works funded and wars declared, the loyalty belongs to the constitution. When the constitution is used to discover a right of a mother to kill her unborn child, or for two (or more) perverts to "marry", or forbids prayer or religious monuments, or to command pharmacists to sell contraception, then these laws, no matter how much they ostensibly rely on the constitution, do not have to be obeyed. If we obey them, that is not out of civic obligation but to avoid some greater harm.