Purse Strings

What makes Congress and elections anymore is money. Lots of money. And the biggest bankrollers of especially Congressional Elections are corporations. Koch, GE, Citibank, Goldman. These, and many others, are the big players. And right now these companies are not happy with Trump. They have all stated publically that they do not like the uncertainty of what he is doing and how it could hurt their businesses.

Trump is trying to appeal to his base in especially the midwest and south. But if he pisses the money people off enough then you damn well know they will be on the phones with their bought-and-paid-for-Congress Critters telling them to go after Trump. They are in it for the money. And if Trump is costing them money...or even perceived to cost them money...then he is really playing with fire.
http://www.cnn.com/2017/01/31/politics/immigration-ban-orders-donald-trump-economics/index.html