Every action has a counter action. this is a fight for the greatest, most wealthy, most powerful country in human history. Nothing is that simple. It is a massive, complex battle.
So, what if President Trump got up this morning and "Declared Martial Law"? If he hasn't done all the work of getting his cabinet on board and the military brass on board, then it would simply blow up.
Scenario 1 - Pence and some military leaders are not on board. Trump declares Martial Law. Pence goes to Congress. In lightning fashion, they convene a panel and declare President Trump unfit. Pence signs it. Trump is removed until he can object. Pence cancels the order and arrests anyone who was on board with Trump.
Scenario 2 - Pence is on board, but some of the key military leaders are not. Leaders slow roll the response while the Senate holds a 2 hour impeachment hearing. Trump is removed
So, for the love of God get it finally!!! It's not a simple thing that the President is trying to pull off. If he fails, it is not for lack of trying.
I think some people think it’s like Michael Scott declaring bankruptcy in The Office: “I declare bankruptcy!”