Transcript for Democrats launch bid to scuttle Trump's national emergency over border wall funding

It's been exactly a week since president trump declared a national emergency to get billions of dollars congress would not give him to build his border wall. And as he expected states are now suing. We will have a national emergency. And we will then be sued and they will sue us in the united -- get. Even though it shouldn't be there and we will possibly get a bad ruling. And today another challenge to president Robert executive authority. House Democrats filing a resolution to block this declaration. Speaker Nancy Pelosi told her democratic colleagues in a letter. The house will quote move swiftly to pass the master it'll then go to the senate for a vote and then the president's desk. I thought an emergency with floods in Iowa. OK but he has put that out it had I don't think it's going to be found constitution how the president with this declaration is trying to get an additional six and a half billion dollars for the wall. On top of the one point four billion dollars congress approved by shifting money from other projects. Most of it would come from the Department of Defense money intended for counter narcotics programs and emergency military construction. And is doing environment pounds to power of the Paris. Congressional Democrats are using their new found power to force Republicans to cast to typical boats. And knicks this national emergency while some Republicans may very well vote with Democrats of the president could however. Veto the measure but it is highly unlikely the votes will be there to override that veto. Stephanie promise ABC news Washington.

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