Professor Jonathan Turley of George Washington University is not a conservative. Yet even he is pointing out that Trump does indeed have the authority as president to declare a national emergency to build the border wall.
He writes at The Hill:
Yes, Trump has authority to declare national emergency for border wall
Congress has refused the funds needed for the wall, so Trump is openly claiming the right to unilaterally order construction by declaring a national emergency. On its face, that order would undermine the core role of Congress in our system of checks and balances. I happen to agree that an emergency declaration to build the wall is unwise and unnecessary. However, the declaration is not unconstitutional. Schiff, now chairman of the House Intelligence Committee, insists that Trump “does not have the power to execute” this order because “if Harry Truman could not nationalize the steel industry during wartime, this president does not have the power to declare an emergency and build a multibillion dollar wall on the border.”
The problem is Trump does have that power because Congress gave it to him. Schiff is referring to the historic case of Youngstown Sheet and Tube Company versus Charles Sawyer, in which the Supreme Court rejected the use of inherent executive powers by President Truman to seize steel mills during a labor dispute. He wanted to claim a national security emergency if steel production halted during the Korean War. In a powerful check on executive authority, the Supreme Court rejected his rationale for unilateral action. The Supreme Court was correct. But that was in 1952.
More than two decades later, Congress expressly gave presidents the authority to declare such emergencies and act unilaterally.
Of course, if Democrats would stop opposing just because they hate Trump, he wouldn’t have to do this at all.