Another "Back of the Queue" factor Any POTUS has to field is the effect any deliberate US discrimination might have on NATO. The UK is currently one if not the only European NATO country meeting the 2% GDP spend on defence, that might go and the US would be left either to abandon NATO or make good the difference and convince the EU member NATO states to cough up and start putting their hands in their pockets.

World markets might be slowing but there is still growth there, the EU has been stagnant for years and behind that there is the prospect of future financial crises in Greece, Italy, Spain, Portugal and France. Our best prospects are to be found trading world wide without us being shackled to Europe.