Like him, I need proof, not promises:

If I thought the proposed legalization was really one time only, and that we had figured out a good way to separate the good, decent people from the terrorists, gang-bangers and assorted felons, I’d get beyond my hesitation (and probably my better judgment) to make accommodations for those millions to continue to work hard and enjoy a better life with their families — like my immigrant ancestors got to do. I’d rationalize that it was the humane thing to do even if it might not be the smartest thing to do. But I need, up front, to be confident it is not a ruinous thing to do.