There is a form of manipulation in social psychology called “lowballing”. It’s used frequently with car dealers. You are quoted a price, the customer drives the car around, makes a commitment to buy the car and then the car dealer starts adding costs to the price originally offered. Since the customer has already committed themselves emotionally to buying the car, they pay the extra cost. This article shows that Trump is changing his tune and showing Republican elites that he isn’t serious about everything he promised his supporters.
Read more in The Guardian