You're right of course, and I am as certain of this as I am that President Trump will get his wall/fence/whatever it ends up being called ... though in doing so he may save the Democrat/Left from their dilemma with their crazy-as-all-get-out base (an outcome I think Pelosi and Schumer secretly hope for).
I believe you are right.. the democrats would much prefer Trump tho do this on his own. That way they could not say that they agreed. It looks as if Trump must declare a crisis.