The surge is especially pronounced in Texas, where voters are deciding closely watched Senate, House and governor's races. More than 6.3 million Texans had voted early as of Wednesday, compared with 4.2 million at the same point four years ago, a 50% increase.

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.