Senator Kirk is the second-most-vulnerable incumbent this cycle. A Republican in a blue state, Kirk already faces tough competition, starting with two-term Rep. Tammy Duckworth (D), who announced on March 30. She flew Black Hawk helicopters for the US Army in the Iraq War, and lost both legs in an attack. Other Democrats may enter the race.
Kirk is one of the most moderate Republicans in the Senate, which gives him a fighting chance in Illinois. But it also opens him up to a primary challenge. Former tea party Rep. Joe Walsh (R) is thinking of running, which could pull Kirk to the right.
Cook Political and Sabato call the race a tossup. Rothenberg-Gonzales calls it tossup/tilt Democrat.