Tammy Duckworth has defeated incumbent Sen. Mark Kirk.
Duckworth is a second-term congresswoman who once led the Illinois Department of Veterans Affairs, according to the Associated Press.
Democrats have had Illinois penciled in the "win" column for months as they mapped a strategy to win back control of the Senate. Kirk is only the second Republican to represent Illinois in the Senate in more than three decades.
Note: Official election results will be available following the proclamation by the State Board of Elections on Monday, December 5th, according to the Board's website.