EXCLUSIVE: Emerging GOP leader backing Trump's use of Alien Enemies Act at Supreme Court

In their brief, America First and Gill argue the president has "absolute authority" under the Alien Enemies Act to determine when an invasion has occurred, and that this decision is "not judicially reviewable."

The brief argues that "the evidence is that TdA has invaded the United States at the direction of the Venezuelan government and continues to invade, attempt to invade, and threaten to invade the country; perpetrated irregular warfare within the country; and used drug trafficking as a weapon against American citizens." 

In a statement to Fox News Digital, America First senior counsel James Rogers said, "The notion that a single unelected judge may take it upon himself to micromanage the defense of our nation is an unprecedented and complete corruption of the separation of powers, which is a bedrock feature of our Republic."

"AFL is proud to join with Rep. Brandon Gill to stand up for the rule of law and to protect our American citizens," said Rogers. 

"No plaintiff is entitled to use the courts to frustrate the president's exercise of clear constitutional authority," added America First Vice President Dan Epstein.

Trump issued an executive order on March 15 titled "Invocation of the Alien Enemies Act Regarding the Invasion of the United States by Tren De Aragua." In the order, Trump stated that TdA is sponsored by Venezuelan socialist dictator Nicolás Maduro with the goal of "destabilizing democratic nations in the Americas, including the United States."

The Trump administration's appeal described the restraining order as a "massive, unauthorized imposition on the Executive's authority to remove dangerous aliens who pose threats to the American people." 

In the administration's petition to the Supreme Court, Harris said this case "presents fundamental questions about who decides how to conduct sensitive national-security-related operations in this country - the president, through Article II, or the judiciary, through TROs [temporary restraining orders]."

She said the Constitution "supplies a clear answer: the president," adding, "The republic cannot afford a different choice."