President Donald Trump on Tuesday signed a memorandum that would bar undocumented people from being counted in the 2020 census for purposes of Congressional apportionment, a move that almost certainly will be challenged in court, as was his U.S. Supreme Court-blocked attempt to add a citizenship question to this year’s census.

“I have accordingly determined that respect for the law and protection of the integrity of the democratic process warrant the exclusion of illegal aliens from the apportionment base, to the extent feasible and to the maximum extent of the President’s discretion under the law,” Trump’s memorandum reads.

It’s not clear how census workers would determine who is a citizen and who is a non-citizen, however, because census workers are prohibited from asking citizenship questions. Trump’s memorandum doesn’t include how his order could be fulfilled.

Legal experts on Tuesday were quick to say that Trump’s move was unconstitutional, and would likely not withstand a court battle.

Elizabeth Wydra, president of the Constitutional Accountability Center, responded to Trump’s order on Tuesday. 

“The Constitution’s text is clear. The federal government has a constitutional obligation to count all people living in the United States, whether they are citizens or noncitizens,” Wydra said in a statement. 

“The Constitution says count ‘persons’ not citizens. Trump lost in court, backed off last summer & the census is already in progress. His unconstitutional EO today, directing a count of only citizens is red meat for his base & an effort to distract from Covid & his other disasters,” Tweeted Joyce White Vance, a University of Alabama law professor and former U.S. attorney.

Alabama Attorney General Steve Marshall on Tuesday applauded Trump’s decision, and said in a statement that the move will protect the integrity of the census.

“When the states’ Congressional seats and Electoral College votes are divided up, representation should be based on those people who reside in their states and this country lawfully,” Marshall said in a statement. “A contrary result would rob the State of Alabama and its legal residents of their rightful share of representation and undermine the rule of law. If people are in our country in violation of federal law, why should the states in which they reside benefit from such violations of federal law?”

Marshall and U.S. Rep. Mo Brooks, R-Alabama, in 2018 filed a lawsuit against the U.S. Census Bureau challenging the bureau’s policy of counting all people, regardless of their citizenship status. In August 2019, a group of attorneys general from 15 states, and the District of Columbia, filed to intervene in Alabama’s lawsuit.

“No individual ceases to be a person because they lack documentation,” said New York Attorney General Letitia James, announcing the group’s intervention in the suit. “The United States Constitution is crystal clear that every person residing in this country at the time of the decennial census — regardless of legal status — must be counted, and no matter what President Trump says, or Alabama does, that fact will never change.”