Kinzinger filed his exploratory paperwork to run against Halvorson in February, but he has been on duty in Iraq since then. He reported raising $17,000 in the first-quarter fundraising period that ended on March 30.

Halvorson picked up the seat for Democrats in 2008, when former Rep. Jerry Weller (R) stepped down. She defeated Chicago-area concrete magnate Marty Ozinga (R) with 58 percent of the vote.