... unless he calls for a national emergency?

but the National Emergency thing could be leveraged by democrats in (at least) two ways:

First, if he thinks he can shift money around due to the national emergency declaration, it diminished the justification for the shutdown. That might give Senate GOPers a reason to vote for funding bills without specific wall funding (b/c he's getting the money elsewhere already) and re-open the government.

Second, it gives Dems a cudgel to bash him (and his bad, callous judgment) with. Namely, he reacted to the border situation -- which is basically unchanged over the past two years despite an entirely GOP-controlled government -- as if it were 9/11 (or insert other most infamous national emergency here). "Disrespecting the victims of 9/11" is a tired trope, but usually it's GOPers trying that gambit so their base is primed to be sensitive to it.

Trump doesn't have the clout to pull off a phony emergency. Republicans know what they saw, same as all of us. He's done.

The reasonable reaction would be whoa wait a minute... why is this an emergency now but wasn't a week ago?