After considering a run in a neighboring district, businessman Bill Johnson (R) decided to challenge two-term Rep. Charlie Wilson (D).
Johnson, an Air Force veteran, had been exploring a campaign against Rep. Tim Ryan (D) in the adjacent 17th district, which includes Johnson's residence right near the district line. But in challenging Wilson, Johnson is opting instead to run in a much more conservative district that voted narrowly Republican for president in 2004 and 2008.
Wilson also lives just outside the boundaries of the 6th district.
Johnson has until Thursday to collect the signatures of 50 qualified Republican voters. He said he's raised more than $107,000 for his campaign.
Veterinarian Donald Allen is also seeking the GOP nomination in the May 4 primary.
Wilson was re-elected in 2008 with 62 percent of the vote against Richard Stobbs (R), who spent less than $5,000 on his campaign.
Former Rep. Jim Traficant (D), who was expelled from Congress in 2002 and served a seven-year prison sentence, is planning to run in either the 6th or the 17th district. He hasn't said whether he will run with a party affiliation.