The Supreme Court on Monday rejected a push for California to set aside thousands of mail ballots from people President Trump’s administration claims are noncitizens, a decision that comes on the eve of the pivotal midterm elections.

The high court refused to intervene in a case involving 20,000 people the Republican administration flagged as likely noncitizens on the largely Democratic state’s voter rolls.

It was the latest in a flurry of election-related litigation the day before the midterm elections, which will decide control of Congress for the last two years of Trump’s second term.