Re(2): On Trump's Declaring a National Emergency over the Border wall Posted on 2/12/2019 at 16:00:23 by Bill Crawford, (14)
According to the below-linked article, it looks like Trump has the executive authority to redirect existing unallocated federal funds so as to provide sufficient money to build his wall; this, without declaring a national emergency.
I have a feeling that this is the way the situation might play out.