After two weeks of resistance, President Trump abandoned his plan to get a citizenship question on the 2020 census. But that doesn’t mean he’s given up on the idea of collecting information about the citizenship status of everyone living in America.

Trump issued an executive order on July 11 directing federal agencies to turn over to the Department of Commerce all citizenship data they have, which he said would “greatly inform a wide array of public policy decisions,” including the drawing of new legislative districts in 2021.

“Some states may want to draw state and local legislative districts based upon the voter-eligible population,” he said.

According to research by the National Conference of State Legislatures, 21 states explicitly require the use of census data for drawing legislative districts, presumably excluding them from using the aggregated federal agency data for that purpose. But with redistricting based on the number of citizens instead of total population expected to shift political power away from urban areas that tend to vote Democratic and toward rural areas that tend to vote Republican, it seems likely that at least some blue states would choose that option if it was available.

That would probably start a legal battle that could end up in the U.S. Supreme Court. The court has ruled that total population is an acceptable basis for drawing legislative districts that ensure one person’s vote is equal to another’s but not necessarily the only acceptable basis. (FIVETHIRTYEIGHT, NATIONAL CONFERENCE OF STATE LEGISLATURES)