Everyone, including Bush, understands that 6K troops will not seal the border. A 100,000 strong force would not be enough! They will simply go around it.
This is why the interior and ways of reducing the pressures are required to take some of the pressure off the border so that we need not put all our resourses in that endeavor and we have some left to deal with the implementation of screening and documentation for those who are here already.
We have finite resources to apply to this, and it must be done quickly and effectively.
It's like dealing with a fire ant problem. If the neighbors don't treat their property, the fire ants simply relocate. We have to deal with this along a broad spectrum of individual problems. All of it together will defeat anything we put on the border if we don't address it all.
Worse than that, the States and localities will refuse to participate, if they perceive they are being hurt by the Fed actions. Everyone has to participate or it all goes down the drain, as in 1986.
That is why you need security in depth. A wall alone will not work. Remote sensing alone will not work. 100,000 boots alone will not work.
And even if you couple all three together, it still will not work UNLESS THERE IS A TRUE DESIRE IN THE GOVERNMENT TO SEE IT DOES WORK.
And IMO, that is the key ingredient that is missing here.