President Donald Trump will try to exclude undocumented immigrants from 2020 census results through a memo he signed Tuesday.

The document would seek to have the Commerce Department, which oversees the Census Bureau, count only U.S. citizens and certain immigrants for divvying up the 435 seats in the House of Representatives. Trump, who has made divisive immigration policy a center point of his political career, previously sought to add a citizenship question to the 2020 census but the Supreme Court last year ruled the effort violated administrative law.

Trump’s memo said that including undocumented immigrants in apportionment would “create perverse incentives encouraging violations of Federal law” for states like California, which may have more than 2 million undocumented residents.

“My Administration will not support giving congressional representation to aliens who enter or remain in the country unlawfully, because doing so would create perverse incentives and undermine our system of government,” Trump said in a statement. “Just as we do not give political power to people who are here temporarily, we should not give political power to people who should not be here at all.”

Tuesday’s memo will likely face a court challenge, as groups such as the Mexican American Legal Defense and Educational Fund, American Civil Liberties Union and more than a dozen states have previously filed suit over the president’s conduct of the census.

Several groups, including the National Democratic Redistricting Commission, previously said they plan to challenge the memo after media reports about it surfaced last week.

About 10 million undocumented immigrants live in the United States, according to a 2016 estimate by Pew Research Center. Most of them are concentrated in large states like California, Texas, Florida and New York. The Pew estimates also noted Nevada as having the highest percentage of undocumented immigrants at 7 percent. Vermont had the lowest undocumented population, at about 0.1 percent of the state.

After losing the Supreme Court case over the citizenship question, Trump directed the Census Bureau to collect citizenship information through administrative records, an order that faces an ongoing federal court challenge.

The memo also represents a reversal of federal government policy. The Commerce Department has argued since the 1980s that there is a constitutional requirement to count every person living in a state for apportionment purposes.

The Constitution and authorizing statute for the Census Bureau make no differentiation between immigrant and native-born residents. Loyola Law School professor Justin Levitt, who worked as a Justice Department attorney on Voting Rights Act issues under the Obama administration, argued that makes it clear the White House memo would fail a court challenge.

“The only, and I mean only, plausible understanding of this legal argument — and I hesitate to even call it a legal argument because it is really a political one — is that the word ‘in’ doesn’t mean what the word ‘in’ means,” Levitt said.

The memo argues that statute requires the Commerce secretary to send census data to the president, which is then disseminated to Congress, which gives him authority to determine who is counted for apportionment.

A 2012 Congressional Research Service report noted the broad language of “whole number of persons” in the constitution might require a constitutional amendment to exclude noncitizens from the apportionment count.

Rep. Mo Brooks, R-Ala., and the state of Alabama have pursued a federal suit against the administration since 2018 seeking to exclude undocumented immigrants from the data used to apportion congressional seats. Brooks and the state argue that undocumented immigrants do not “reside” in their current state for apportionment purposes because they do not live there legally.

The state’s attorney general, Steve Marshall, has argued that states like California disproportionately benefit from including undocumented immigrants while Alabama stands to lose a seat following the 2020 count.

Last year more than a dozen states, the Mexican American Legal Defense Fund and major cities throughout the country intervened in the case, fearing the administration wouldn’t fully defend the inclusion of immigrants in census results. The case is currently in the process of legal discovery.

Congressional Republicans and a handful of Democrats have sought to exclude undocumented immigrants from the census for decades. The Federation for American Immigration Reform and a group of representatives brought an unsuccessful suit before the 1980 census seeking to exclude undocumented immigrants from the apportionment count.

Several times in the intervening decades, Congress has considered standalone bills or amendments to spending legislation that would exclude undocumented immigrants from the count. However none have passed into law.