Illinois state Sen. Tom Cullerton says he's decided not to run for Congress to replace Democratic U.S. Rep. Tammy Duckworth.

Cullerton is a first-term Democratic senator from Villa Park. According to reports, he says he wants to focus on running for re-election to the Illinois Senate. Duckworth is leaving the 8th Congressional District seat to run for U.S. Senate.

Cullerton says he doesn't regret considering a move up. He says "the opportunity for a congressional seat doesn't come along very often."

His departure leaves businessman Raja Krishnamoorthi of Schaumburg and state Sen. Mike Noland of Elgin as Democratic candidates in the race.