CHICAGO (AP) -- Longtime Republican Congressman Don Manzullo has lost a grueling primary election to freshman Congressman Adam Kinzinger in north-central Illinois.

There's no Democrat on the ballot, so Kinzinger is headed back to Washington.

The 16th Congressional District race was the only incumbent versus incumbent race in Illinois and pitted the veteran lawmaker against the former Air Force pilot.

That's because new congressional map drawn by Democrats put much of Kinzinger's old district into Manzullo's. Kinzinger decided to run in Manzullo's instead of challenging Democratic Congressman Jesse Jackson Jr., who easily won the Democratic nomination Tuesday.

The new 16th District curves through north-central Illinois from the Wisconsin state line to the Indiana border.

Kinzinger first won office in 2010 with strong tea party support, including an endorsement former Gov. Sarah Palin.