Transcript for 'Start Here' podcast: Trump to declare national emergency

And we're gonna move on now to president trump he is determined to build his border wall with or without congress. Now he's preparing to declare a national emergency and take executive action. To the president what says he will sign the bipartisan border security bill passed by the house and senate to avert a government shot down. But he wants to dip into funds from the Pentagon to fulfill his signature campaign promise ABC's Brad milky has more on the legal challenges that are sure ahead. Good morning Brad. As yet congressional leaders were psyched when they found the president was gonna sign this bill they were less site when he found out he. He also wants declare a national emergency. Usually you declare a national emergency for summing like a war or even an international dispute the president focused pulling the trigger because after months of negotiations congress will not give him what he's deemed necessary. ABC senior national correspondent Terry Moran told me we have never seen anything like this before which means were new legal territory to. In this instance. The president under the laws that have been passed by congress could redirect Department of Defense funds which are used for military construction. Towards then national emergency there's also some civil construction funds that the president could use. The question is is that legal is it a true national emergency and the bigger question in some ways around that issue. Who gets to decide if we ever asked a president to come to justify himself over what a national emergency know. Having said that that that the laws around these national emergency say the president just specify what the emergency as. And the question is would the court's second guess a president. About what is or is not a national emergency. Not a lot more on start here later this morning. Listen on apple podcast refute it podcasting app today GO our thanks to Brad.

This transcript has been automatically generated and may not be 100% accurate.