WASHINGTON — The U.S. Supreme Court said Friday that it will take up the battle over a citizenship question for the coming census, agreeing to hear and decide the case before the court's term ends in late June.

Eighteen states, several of the nation's largest cities and immigrant rights groups sued the government over its decision to ask about citizenship on the 2020 census form that goes to every U.S. household. They said the question would make immigrants reluctant to respond to census takers, resulting in an undercount of the population.

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The Supreme Court will hear arguments in the case in April.

A census is required every 10 years by the Constitution. The results determine the size of each state's delegation in the House of Representatives. And census data is used to calculate a local government's share of funds under many federal programs.

Commerce Secretary Wilbur Ross has said the question was added at his direction, after he received a letter from the Justice Department that said the data was needed to properly enforce civil rights laws. But Federal District Court Judge Jesse Furman of New York said the evidence at a trial on the issue revealed that Ross's claim was a pretext.

Furman concluded that Ross had asked the Justice Department to send the letter, which showed that he "made the decision to add a citizenship question well before he received DOJ's request." The judge also found that including the question would violate a federal law requiring the government to get as accurate a count as possible, because it would "materially reduce response rates among immigrant and Hispanic households."

The Trump administration argued at the trial that questions about citizenship or country of birth have been asked during all but one census from 1820 to 2000. The form includes many demographic questions, the government said, about race, sex, Hispanic origin and relationship status.

While the challengers and the government differed about whether the judge got it right, they agreed that the Supreme Court should take the case now, bypassing the normal process of letting a federal appeals court rule first. The Justice Department said the deadline for preparing the census form is this June, so the justices should take the case "in light of the immense nationwide importance of the decennial census."

That notion was also advanced in a legal brief filed by House, controlled by Democrats, which opposed including the question. But it added that while House Republican leaders do not agree about putting the issue on the form, they "do agree that, if the court chooses to grant review, it should resolve the matter expeditiously."