This is just a thought. Congress is the most imperial branch of government in the US. They represent a domestic constituency who holds them accountable for domestic policies. In international relations, they are not held accountable by their constituency nor do they engage in any form of diplomacy.
The President is the most connected with foreign policy, so a President’s choice is constrained by diplomacy and other state actions. A president is held accountable by the international community.
Congress is imperialist and cruel to American allies and is responsible for a large amount of ill-will towards the US. Congressional leaders issue imperial orders in the form of benchmarks with restricted funding to allied countries like Colombia, South Korea, Iraq, Dubai, and others, while denying trade rights.
The great reforms in foreign policy shifted decision-making from Congress to the President. One example if FDR’s reform of trade and tariffs. Congress used to raise import tariffs as a matter of domestic policy – so it could screw the rest of the world. American voters did not see the immediate pain these policies caused, becaused they were detached from the effects of Congressional foreign policy.
FDR and Truman shifted trade policy away from Congress to international diplomats and the GATT/WTO. States function like a constituency to hold the international organizations and other states accountable for trade disputes. This means there is more cooperation and less disruptions.
Well, there’s probably more to it than representation and constituencies. For some reason, Congress is kinda evil in practice and I’m curious why.