President Donald Trump thinks if he says something, it must be true. And if he says something long enough and loud enough, he's convinced the American people will think it's true, too. We've seen him do this over and over in his first two years in office.

He won't take no-or the truth-for an answer.

To no one's surprise then, on Friday he declared a national emergency over Congress' refusal to give him $5.7 billion to fulfill a campaign promise. Namely, to build a wall between us and Mexico. Putting aside that this promise is already broken because he said Mexico was going to pay for that wall and it won't, Trump apparently forgets that he made a bigger promise to all citizens when he was sworn in: "I will faithfully execute the Office of President of the United States, and will to the best of my ability, preserve, protect and defend the Constitution of the United States."

Now we face a constitutional crisis.

The Constitution outlines the major players' duties in this fight. Simply put:

• The legislative branch makes the laws and appropriates the funds.

• The executive branch enforces the laws.

• The judicial branch interprets the laws.

There's a reason the legislative branch, i.e., House and Senate, is first. Just as there's a reason that the courts are third.

Congressional leaders, Democrats and Republicans alike, have no choice but to challenge him. Let's be clear that failure to do so would set a dangerous precedent. Party affiliation should be less than nothing in this fight.

We will have a genuine national emergency on our hands if Congress and then the judiciary don't put the president in his place.