I think it would be fair to say that the same Republicans who are backing Trump now will throw a major hissy fit with a collective gnashing of teeth if the next Democratic President tries to declare a national emergency to fund a pointless project he or she is pushing to appease their voting base.
Excerpt from the article...
Lawmakers of both parties have raised concerns about Trump declaring a state of emergency, and even some Republican say it could set a precedent for a future Democratic president to go around Congress.
Speaker Nancy Pelosi and Senate Minority Leader Chuck Schumer said in a joint statement, “Declaring a national emergency would be a lawless act, a gross abuse of the power of the presidency and a desperate attempt to distract from the fact that President Trump broke his core promise to have Mexico pay for his wall.”
Senator Susan Collins, a Republican from Maine, said Trump’s use of a state of emergency is of “dubious constitutionality” and will face challenges in court.
“I certainly have concerns about using the emergency declaration for this set of circumstances but let’s see what happens,” said Senator Roy Blunt, a Republican from Missouri.
And another excerpt...
Democrats raised concerns about the potential precedent of expanding executive power and looked towards legal options.
“I think declaring a national emergency where there is no national emergency is not good for the president to do and not good precedent for future presidents,” said House Majority Leader Steny Hoyer.
Meanwhile, Pelosi told reporters that she would consider a legal challenge to the declaration – something that most observers say is inevitable and would likely result in a victory.