At issue is whether 4th Congressional District candidates Alderman Byron Sigcho-Lopez and Mayra Macías have enough valid petition signatures.
The Illinois State Board of Elections ruled that neither of them had enough and removed them from the ballot.
Both candidates were running to replace outgoing Congressman Chuy Garcia.
The minimum signature requirement was 10,816. Both Sigcho-Lopez and Macías said they submitted more than enough, but those submissions were challenged.
The race has been controversial since Congressman Chuy Garcia's last-minute decision not to seek reelection, essentially ensuring his chief of staff, Patty Garcia, would be the only Democrat on the primary ballot.
Patty Garcia is not related to the congressman.
Lyons Mayor Chris Getty is also running as an independent candidate and his petitions were not challenged.