IMO the Repub leadership has the smarts of a pigeon.
And in this situation:
The money is only the beginning of the problem.
Congress will pass a law forbidding building a wall. They may very well override a veto. Their donors simply are not going to stand for a wall.
The Repubs would be suiciding as a Party.
Any idiot could figure that out.
Of course, the Repub leadership over the years have shown themselves to be “special olympics” types of idiots.
Dumber than the usual idiots.