CHICAGO  — A well-known Illinois state senator dropped her bid Sunday for the U.S. House seat vacated by Jesse Jackson Jr., narrowing the field and consolidating key support behind another Democrat in a race where gun control has emerged as a central issue.

State Sen. Toi Hutchinson, targeted in recent days by critical anti-gun campaign ads funded by New York Mayor Michael Bloomberg’s political action committee, said she was leaving the race and swinging her support to former state Rep. Robin Kelly. The major shake-up came with just nine days to go before the Feb. 26 primary.