Thesis: The executive branch is becoming too powerful.
Antithesis: If that ever happened, the white-collar desk jockeys at the IRS would rise in revolt against authoritarianism.
Synthesis: Democracies cannot be authoritarian as long as they pass the 
test.
Eh, you just need to write a law that says "this is dictatorship now" and have a Supreme Court that will say "Yup this is legal".
Job done.
All you really need is capture of the legislator and the court. The court can make up whatever it wants.
Oh and the president can also just assassinate everyone that opposes him now and they already ruled that it's totally legal no matter who he's doing that to. So like, would you oppose the president? All he's gotta do is make a few people disappear and the rest will suddenly do whatever he wants. Enough fear of being next to die and they'd all fall in line behind the new dictator.
Shout outs to the conspirators who murdered Julius Caesar and then shrugged and dismantled their Republic anyway