End the talk and just do it. Tell Congress that is what is occurring and if they don’t like it they can approve funds to let DHS do it. My guess is that they’ll scream and let it be done instead of approving direct funds. They get political cover and Trump gets the wall.
Actually ‘ it is a little known fact that congress prohibited the use of defense money for the wall. But that violates separation of powers on national defense and we now own SCOUS.