....if he did it this year, he would face huge problems with his base politically.
Also, Trumps style of negotiation seems to be to agree to something, then when the other side relaxes and makes plans to take back the promise so as to pressure the other side to make concessions.....although it could just be a flip flop - but personally, I think it is a negotiation tactic he likes to use & May have done in the business world.