AIPAC doesn't directly contribute to the campaigns of American politicians. They do it through other political action committees (PAC's). Unfortunately, supporting candidates they like is not all they do. They also move against candidates they don't like in a number of different ways. AIPAC makes it their business to know the backgrounds, weak points, and skeletons in the closets of American congressmen. If you are an American politician, you just don't want to irritate these people. They have too many ways they can hurt you.
Fighter jet of unknown nationality 'interfered' with 8 Turkish jets near Syria (Reuters)
from the article: Netanyahu's speech to Congress shows America will buy anything