They sure do know what would happen... their campaign contributers who want an endless supply of cheap labor at taxpayer expense might stop giving them money.
You, on the other hand get your facts from VDare, World Net Daily and Free Republic.
Do you have some evidence to back up that explosive claim?
If you think that is the problem then you need to advocate CFR. That is not a popular subject at FR, you might get tarred and feathered. Or banned.