The U.S. Supreme Court on Friday rejected a request by President Donald Trump's administration to halt a trial set to begin on Monday that will test the legality of the government's contentious decision to ask people taking part in the 2020 national census whether they are citizens.

The justices announced the action in a one-sentence order. Three conservative justices — Clarence Thomas, Samuel Alito and Neil Gorsuch — said they would have granted the request for an indefinite postponement of the trial. Trump's new appointee to the nine-member court, Brett Kavanaugh, did not state publicly how he voted on the matter.

The decision benefits the 18 states challenging the census citizenship question in part because such a postponement could have made it impossible to resolve the dispute before census forms are printed starting next year.