Congress had a budget; Trump agreed to it. Then, Rush et al puked, and Trump reneged - he lied. However, lying is his only real talent/skill so he employs it as often as possible.
But his lying provides a pretty simple way out of this...I didn't think of it, but I wish I had:
Since "The Base'" gullibility resides at a ludicrous level....all Trump really needs to do is tell them "'The Wall' is built and working great!" Shit, it's guaranteed they'll buy it....the Russians will assemble all kinds of "Mission Accomplished" memes which will be forwarded in countless emails as well as shared over-and-over on social media.
Trumptards will swell up, beat their chests and scream "I told you so. TRUMP! MY MAN!!"
After the circus, everyone goes back to work, and we move on.