U.S. Rep. Cheri Bustos says she's decided not to challenge Republican Mark Kirk for his U.S. Senate seat.
Bustos had been mulling a run, but said Monday that she won't run now that U.S. Rep. Tammy Duckworth is in the race for the Democratic nomination.
Duckworth announced her candidacy in a largely autobiographical video posted Monday to her campaign website. She is the first major candidate to announce a challenge to Kirk, a first-term Republican.
Bustos says she's not formally endorsing anyone yet, but praised Duckworth's record and called her a "strong fighter for working men and women and veterans."
Other Democrats who've indicated interest in running in 2016 include U.S. Reps. Bill Foster and Robin Kelly.
Republicans mulling a run include former tea party U.S. Rep. Joe Walsh.
