Trump failed on Mexico paying for the wall and now wants the US military to pay: Former federal prosecutor
President Donald Trump suggested he will declare a national emergency on the border with Mexico as a way to use military funds to erect a wall. (AFP / Brendan Smialowski)

Former federal prosecutor Renato Mariotti said that President Donald Trump declaring a national emergency is unnecessary since he broke his campaign promise that "Mexico will pay for the wall."

Mariotti explained that once Trump’s national emergency declaration goes through the courts, it will most likely be found unconstitutional.

"From a constitutional perspective, this is a problem. It lets a simple majority of Congress give away their authority. Then essentially they need a two-thirds majority to override Trump. I suspect the law will be found unconstitutional," he told CNN's Chris Cuomo on Friday.

Former White House lawyer James Schultz argued that the funds were necessary to pay for the military at the border, in which Mariotti quickly fact-checked.

"Instead of Mexico paying for the wall, now the United States military is paying for it. The military at the border is discretionary. It's part of a Trumped-up effort by the president to try to make this sound like there's some sort of crisis," Mariotti said.

"The fact of the matter is that what the statute says is that the armed forces have to be necessary for the operation. I don't think anyone, particularly the trial judge that's ultimately going to make findings of fact, is going to conclude you absolutely need the military for this operation," he added.

Watch below via CNN: