IANAL, but i think there's an argument to be made that a congressional vote held under duress (like any other contract) is invalid. Ultimately, the question of

IANAL, but i think there's an argument to be made that a congressional vote held under duress (like any other contract) is invalid. Ultimately, the question of who controls the US government (and its monopoly on the legitimate use of force) falls to "who can order the army to collect taxes from the states". In the absence (or ambiguity) of guidance from the representatives of the states, the decision would come down to the Chairman of the Joint Chiefs of Staff of the US armed forces, to decide whose orders he takes and to give the nuclear football to somebody.