President Trump's authority in this matter comes from the declaration of emergency as authorized by Congress, and is limited to what is covered by that declaration.
Remember that Obama waited for six months, 20,000 Americans hospitalized, and 1,000 deaths before declaring that declaration of emergency.
I'm sure that he has broad authority pursuant to the Congressional act, but it is not absolute and does have boundaries (which I do not know the limits of).
-PJ
does pence ever get mad or raise his voice?
Pence is explaining it much better with reference to the emergency declarations than Trump did with the over-simplistic “total.”