The Trump administration alleges that about 20,000 noncitizens may be registered to vote in the state, an assertion disputed by the local officials.

In a loss for Donald Trump, the Supreme Court on Monday swiftly rejected the administration’s request that California separate out up to 20,000 mail-in ballots that officials allege could be submitted by noncitizens.

The court in a brief order turned away without explanation an emergency request filed just hours earlier by the Trump administration as part of an unusual last-minute flurry of election litigation. Lower courts had also ruled against the Trump administration.

The court acted so quickly it did not even ask California for its views first, as it normally does in such cases.