A federal judge rejected on Wednesday a Trump administration request to stop California from processing the ballots of up to 20,000 people over allegations they are likely noncitizens, warning it would "wreak havoc" on the midterm elections.

The administration has insisted that immigrants voting is a major problem nationwide, when in fact it is quite rare, as even its own investigations have shown.

Marva Cook was adopted as a toddler and had always assumed she was a U.S. citizen, she told Homeland Security investigators earlier this month, according to the criminal complaint.

Most of the immigrants targeted by federal authorities in California this week for alleged voter fraud had applied for U.S. citizenship and now face charges related to lying on forms or during interviews. Those charges could lead to years in prison and thwart their efforts to naturalize.

The Trump administration is escalating its fight with California ahead of next month's midterm election, warning that local officials who process and tabulate ballots submitted by suspected noncitizen voters are putting themselves at risk of criminal investigation and potential prosecution.