. . . fiscal hawks said they could not support the massive package without more spending cuts. ...
What Trump is doing will be challenged all the way to the Supreme Court, which already ruled the 1996 version of the line item veto unconstitutional.
Trump is a renegade.
Imagine a Democrat president simply canceling programs Republicans passed and firing all the people in them. That's what this is. And that's what the future will bring if Trump gets away with any of this.
It's anarchy, and it's unconstitutional, however much you may agree with the cuts. The Court will set this straight or the federal government is finished as an institution.