Billionaire Ken Griffin has contributed $20 million to Republican Illinois Gov. Bruce Rauner's re-election fund.
Rauner's campaign committee reported the donation from the CEO of the Chicago-based investment firm Citadel on Wednesday.
The eye-popping contribution is the latest sign of how costly and competitive the 2018 race for Illinois governor will be.
It comes as several Democrats are vying for the nomination to try to unseat Rauner in 2018. They include billionaire businessman J.B. Pritzker, who recently put about $7 million into his own campaign fund. Late last year Rauner contributed $50 million of his own money to his campaign account.
Other Democrats running include state Sen. Daniel Biss, Chicago Alderman Ameya Pawar and wealthy businessman Chris Kennedy, who contributed $250,100 to his campaign and lifted contribution limits for the race.