CHICAGO (AP) — Early voting is set to begin for the Illinois primary, but millions of voters won’t have the option because of pending candidate challenges.

Illinois’ two most-populated counties, Cook and DuPage, are delaying until as late as Feb. 21 to wait out final decisions on several races. More than 3.5 million voters, including in Chicago, are affected.

Clerks elsewhere, including in Madison, Pope, Sangamon and Vermilion counties, will start early voting Thursday, but will explain the situation to voters.

One candidate challenge has statewide impact. A judge ruled Democratic attorney general candidate Scott Drury can’t be on the ballot over paperwork issues, but his name is allowed to remain during an appeal. If Drury is ultimately ruled off, votes for him won’t be counted.

Though the decision to delay is up to each jurisdiction, state election officials encouraged them to start in a “timely manner.”