Trump knows that accepting this trifle may very well be a read-my-lips moment for him. This is why he keeps saying “the wall is already being built.” If that’s the case why was the govt shut down? I’m a strong Trump advocate, but I don’t think conservatives and others concerned with border security will buy this; we’ll see it as just one more: “Thank you, Nancy. Thank you, Chuck. May I have another?”
The GOP doesn’t want a wall and wants Trump to fail. He’s playing a very weak hand here trying to play high stakes political negotiating without the support of his own party.