County Clerk Linda Robbins says around 4,000 Monroe County residents participated in early voting this year.
The 2nd district seat is open since Joe Donnelly is running for Senate.
8th District Congressman Larry Bucshon has raised substantially more money than his Republican opponent Kristi Risk.
The 5th district primary has several candidates from both the Republican and Democratic parties.
Senator Dick Lugar faces a tough challenge in the GOP primary there on Tuesday from the state's treasurer, who is running to his right.
U.S. Congressman Mike Pence is running for governor, meaning there is no incumbent in the 6th district race.
A poll by a Republican and Democratic pollster shows Richard Mourdock with a large lead over incumbent Senator Richard Lugar.
Some Republicans say a mailer in support of Senator Richard Lugar encourages Democrats and independents to vote in the Republican primary.
Monroe County says the electronic voting equipment it recently purchased is working well.
Lugar and his wife will have to re-register to vote in Decatur Township for the state's primary election.