Ohio voters have picked the major party nominees for the latest in a string of House special elections with implications for control of the chamber after November's midterms.

Democratic Franklin County Recorder Danny O'Connor is projected to win Tuesday's primary for Ohio's 12th District special election, according to NBC News. While NBC has not called the GOP primary for the seat, state Sen. Troy Balderson leads with nearly all votes counted.

The candidates are expected to emerge from crowded primary fields to compete in an Aug. 7 special election to serve until January. O'Connor and Balderson are also expected to represent their parties in the November general election. The seat, vacated by GOP Rep. Pat Tiberi's resignation, will serve as another litmus test for Democrats as they try to win suburban areas that have recently tilted red.

The minority party hopes to win the 23 Republican-held seats in November needed to take a majority in the chamber. The 12th District sits in suburban Columbus and nearby rural areas, and is wealthier and better educated than the median congressional district. Winning districts like it could prove crucial to Democrats' ability to flip the House.