The deal had already been vetted and he had utter confidence in the dozens of people who had already OK'ed it.
And there was his mistake. The buck stops at the top. In the history of the US no President has stood in front of the American people and told 70% of the country that they were a bunch of racist, xenophobic uneducated people. When something is 70/30 against you, you do not simply dismiss the 70%. You have to at least appear that you are considering their concerns. You do not state it's a done deal, you do not threaten to veto, you do not put your Rep Congress out to hang in the wind, you do not side with rich friends over the American people. Frankly, I was surprised he still had 34% confidence. Another couple months at this rate and he will be down to single digits. Talk about living in a bubble.