Attorney General Letitia James signed on to a multi-state effort on Friday to block President Donald Trump’s administration from using $1.6 billion in federal money for the construction of a wall on the U.S.-Mexico border.

The filing was part of a coalition of 20 states that is being led by California Attorney General Xavier Becerra.

“Diverting funds from key initiatives in order to fund an unnecessary and unwarranted wall is fundamentally irresponsible, undermines Congressional power, and will hurt every American across this nation,” James said in a statement. “We will continue to work with other states in order to prevent this blatant abuse of power.”

The motion argues the president is illegally using executive action to spend the money on the wall, a key campaign pledge for Trump, and violates the U.S. Constitution’s separation of powers principles.

Ultimately Trump wants to send up to $6.7 billion through the Department of Treasury’s Forfeiture Fund to build the wall.

James has pledged to take an aggressive legal posture toward the Trump administration’s policies and has launched an investigation into the president’s failed effort to buy the Buffalo Bills.