I feel the Executive branch is having the most power in the US government system and this is because the President heads it and he acts as the head of the state as well. The President is responsible to implement the laws that are written by the Congress and if the President is of the belief that the law is not in the favor of the will of the people, he can veto the bill which will go back to the Congress and here the Senate and the house can only pass the bill having a two-thirds majority voting.