Vincennes Mayor Joe Yochum will not appear on the November ballot for State Senate District 39.
Yochum said an Indiana Democratic Party procedural error will keep him off the ballot.
The party failed to file required paperwork within three days of the caucus, naming Yochum a replacement nominee.
Republican Jeff Ellington will now run unopposed in November.
Ellington would succeed outgoing State Senator Eric Bassler of Washington.