The U.S. Supreme Court declined today to delay Michigan’s new ban on affirmative-action preferences, a move that will require three public universities in the state to continue admitting students without regard to their race, gender, or ethnicity, according to a report by the Bloomberg news service.

In a brief order issued today, the court let stand a ruling last month by the U.S. Court of Appeals for the Sixth Circuit, which said that the ban — known as Proposal 2, a ballot measure approved overwhelmingly by Michigan voters in November — should go into effect immediately.

The Sixth Circuit’s ruling struck down a deal between the universities and the state’s attorney general under which Proposal 2 would take effect this summer, after the current round of admissions had been completed. Soon after the Sixth Circuit ruled, the universities — the University of Michigan and Michigan State and Wayne State Universities — said they would comply with Proposal 2, although they filed briefs in this case.

Today’s action by the Supreme Court does not represent the end of efforts to thwart Proposal 2. Supporters of affirmative action, led by a group known as BAMN, have sued to overturn it. The court’s move today concerned a motion to delay Proposal 2’s effectiveness while the lawsuit is heard.