Trump's tariff threat appeared to move him away from a previously threatened imminent closing of the border in order to punish Mexico.
Pelosi said in a statement Thursday that Trump was "stealing from appropriated funds". Ted Cruz weighed in on the issue, concerned that a closed border would have a direct impact on his constituents, many of whom are supporters of the president.
Pelosi said members of the House's Bipartisan Legal Advisory Group voted to go to court.
Sixteen Democrat-majority states have already sued Trump over the emergency declaration, filing their challenge before a federal judge in California.
President Donald Trump threatened to slap tariffs on automobiles made in Mexico and close the US-Mexico border if the country didn't stop "massive amounts of drugs" coming into the US within one year. He has since praised the country for doing more. "The president's absolutely right with the pressure he's putting on Mexico", Morgan said.
Trump said that he would give Mexico a one-year warning, before leveling tariffs, calling it "the big ballgame".
Nielsen was creating an emergency operations center and named U.S. Border Patrol official Manny Padilla as an operational crisis coordinator to manage the response from within the different immigration agencies at the Department of Homeland Security.
"I've never experienced anything like this, in all the time I have worked here", said truck driver Juan Sandoval, who joined the line before dawn on Thursday, the fourth day of huge truck lines at the border. Over the Thanksgiving holiday a year ago, Trump claimed he'd already "closed the border" after officials briefly closed the northbound lanes at San Ysidro, California, for several hours in the early morning to bolster security because of concerns about a potential influx of migrant caravan members.
U.S. soldiers walk next to the border fence between Mexico and the United States, as migrants are seen walking behind the fence, after crossing illegally into the U.S.to turn themselves in, in El Paso, Texas, U.S., in this picture taken from Ciudad Juarez, Mexico, April 3, 2019.