The Trump administration’s push to add a citizenship question on the 2020 census hit a roadblock Thursday, when a divided U.S. Supreme Court partially upheld a ruling in favor of challengers who argue the move will cause a substantial undercount of Hispanics and other minorities and benefit Republicans in election districts across the country.

Writing for the court, Chief Justice John Roberts Jr. said the reason given by U.S. Commerce Secretary Wilbur Ross for adding the citizenship question—to enforce the Voting Rights Act—  “seems contrived” and the evidence in the trial record “tells a story that doesn’t match Ross’s decision.”