WASHINGTON — President Donald Trump signed a memorandum Tuesday that seeks to bar people in the U.S. illegally from being included in the headcount as congressional districts are redrawn, a move that drew immediate criticism and promises of court challenges on constitutional grounds.

Trump said including them in the count "would create perverse incentives and undermine our system of government." Seats in U.S. House of Representatives are redistributed every 10 years based on changes in population found in the census.

The Supreme Court blocked the administration's effort to add a citizenship question to the 2020 census form, with a majority saying the administration's rationale for the citizenship question — to help enforce voting rights — appeared to be contrived.

New York Attorney General Letitia James, who, along with civil rights groups, fought the citizenship question in court, vowed to challenge the order.

"No one ceases to be a person because they lack documentation," James said. "Under the law, every person residing in the U.S. during the census, regardless of status, must be counted."

Dale Ho, director of the ACLU's Voting Rights Project, predicted Trump's latest effort also would be found unconstitutional.

"The Constitution requires that everyone in the U.S. be counted in the census," Ho said. "President Trump can't pick and choose. He tried to add a citizenship question to the census and lost in the Supreme Court ... We will see him in court, and win, again."

Trump's latest move comes in the lead-up to the November election as he is trying to motivate his base supporters with fresh action against illegal immigration, which was a mainstay of his 2016 campaign

"There used to be a time when you could proudly declare, 'I am a citizen of the United States.' But now, the radical left is trying to erase the existence of this concept and conceal the number of illegal aliens in our country," Trump said in a statement. "This is all part of a broader left-wing effort to erode the rights of Americans citizens, and I will not stand for it."

More than 92 million households have already responded to the 2020 Census, with the majority doing it online. People can still respond on their own online, over the phone or by mail — all without having to meet a census taker. Only last week, door-knockers started heading out to households whose residents haven't yet answered the questionnaire.

Trump's efforts to add the citizenship question drew fury and backlash from critics who alleged that it was intended to discourage participation in the nation's head count, not only by people living in the country illegally but also by citizens who fear that participating would expose noncitizen family members to repercussions.

The financial and political stakes in the 2020 Census are huge, with Democratic-leaning metropolitan areas with large immigrant populations worried about losing dollars and political representation through Trump's efforts.

After the Supreme Court blocked the citizenship question from being asked, Trump ordered the Census Bureau to gather citizenship data from the administrative records of federal and state agencies. The administration hopes that will help it determine how many people are in the U.S. illegally.

That order is being challenged in the courts and the overwhelming majority of states have refused to share information about driver's licenses and ID cards.

However, four states with Republican governors are cooperating. Iowa, South Carolina and South Dakota recently joined Nebraska in agreeing to share state driver's license information with the Census Bureau.

Democratic members of Congress called the president's memo an effort to depress participation in the 2020 census, especially in minority communities.

"Trump's unlawful effort is designed to again inject fear and distrust into vulnerable and traditionally undercounted communities, while sowing chaos with the Census," House Speaker Nancy Pelosi said. "The House of Representatives will vigorously contest the President's unconstitutional and unlawful attempt to impair the Census."

It's not the first time that an attempt had been made to keep out immigrants living here illegally from the once-a-decade census and the subsequent allocation of congressional seats. In 1979, the Federation for American Immigration Reform and several members of Congress sued, demanding that the 1980 census exclude undocumented immigrants from apportionment. The case was dismissed, said Margo Anderson, a history professor at the University of Wisconsin-Milwaukee.

When a congressman unsuccessfully introduced legislation in 1980 that would have kept undocumented immigrants out of the apportionment count, U.S. Census Bureau director Vincent Barabba expressed concerns about entangling the bureau with immigration policy. He testified that doing so might entail procedures done in other countries, such as maintaining registration lists, that Americans would find disagreeable, Anderson said.

In Alabama, state officials and Republican U.S. Congressman Mo Brooks are suing the Census Bureau to exclude people in the country illegally from being counted when determining congressional seats for each state.

Trump's memo Tuesday is an blatant attempt to suppress the growing political power of Latinos in the U.S., said Thomas Saenz, president and general counsel of the Mexican American Legal Defense and Educational Fund.

The fund, also known as MALDEF, and other civil rights groups are challenging Alabama's effort to exclude people in the country illegally from being counted during apportionment, and they pre-emptively challenged the very issues raised by Trump's memo on Tuesday in a cross-claim, Saenz said in an interview.

"It's lawless but that's characteristic of this administration. We are already challenging it. We anticipated this ridiculousness," Saenz said.

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Associated Press writer Jill Colvin contributed to this report. Schneider reported from Orlando, Fla.