A group of 20 states led by California has formally requested that a federal judge stop President Trump from diverting federal funds to build his wall on the southern US border, according to The Hill.

The preliminary injunction was announced by the state attorneys general as Trump made his way to California to visit a segment of the border wall.

Heading to the Southern Border to show a section of the new Wall being built! Leaving now! — Donald J. Trump (@realDonaldTrump) April 5, 2019

The filing argues that Trump's declaration of a national emergency to divert the funds is unconstitutional, and that irreprable damage would be done if the wall is constructed.

"Notwithstanding the president’s expressed frustration with Congress and the legislative process, he must act in accordance with the procedures established in the Constitution to obtain funding for his border wall," reads the filing.

The injunction request also claims that the wall would cause "possible irreparable arm to endangered species," living near the border, and that the National Environmental Policy Act has been violated due the the Trump administration's failure to study the potential impact of the wall.

The states' request comes just hours after the ACLU similarly asked a federal judge for a national injunction to halt construction on the wall.

Trump declared a national emergency earlier this year following shortly after a 35 day-long partial government shutdown after Congress refused to pass a funding bill granting him his requested amount of funding to construct the border wall. Attorney General William Barr said at the time that Trump had the legal authority and standing to declare the national emergency. And Homeland Security Secretary Kirstjen Nielsen and other immigration officials have since called the situation at the border a crisis. -The Hill

On Thursday, House Speaker Nancy Pelosi (D-CA) said that the House will file a lawsuit to challenge Trump's emergency declaration.

"The House will once again defend our Democracy and our Constitution, this time in the courts," said Pelosi in a written statement. "The President's action clearly violates the Appropriations Clause by stealing from appropriated funds, an action that was not authorized by constitutional or statutory authority"