Republican Bruce Rauner and his wife, Diana, have poured $1.1 million of their own money into Republican party organizations and candidates since the start of 2013.
That's in addition to the $6.5 million the wealthy venture capitalist has contributed to his own campaign for governor, according to the state board of elections.
Mr. Rauner, who won a four-way primary to get the GOP gubernatorial nomination, is financially supporting party organizations and candidates up and down the state to build what a spokesman called a "grassroots" campaign against Gov. Pat Quinn.
Beneficiaries of the Rauners' largesse include Republican Bobby Schilling, of Colona, who has received $20,800 from the couple for his rematch with U.S. Rep. Cheri Bustos, D-East Moline; and Republican candidate Neil Anderson, of Moline, who has received $10,600 from the Rauners for his run against state Sen. Mike Jacobs, D-East Moline.
Dozens of Republican party organizations from Winnebago County in the north to Monroe County in southern Illinois also have benefited from checks from the Rauners.
"Bruce is supporting grassroots organizations because he knows it will take a team effort to beat Pat Quinn in November," Mr. Rauner's spokesman Mike Schrimpf said.
The Republican central committees in Rock Island, Henry, Mercer and Whiteside counties all have received checks of $1,000 or less from the Rauners in this election cycle.
According to the Illinois State Board of Elections, the Rauners have given $7.5 million to Republican committees and candidates since Jan. 1, 2013, including the money funneled to Mr. Rauner's own campaign.
The Rauners also have put $65,000 into the Republican National Committee and gave $20,000 to the Illinois Republican Party in the 2014 cycle.
Mr. Rauner lives in Chicago suburb Winnetka and made roughly $100 million between 2010 and 2012, according to tax returns released as part of his campaign for governor.
He paid about 19 percent of that amount in federal taxes and also donated $13 million to charity, mainly in the education and civic fields.
Financial disclosures show Mr. Rauner owns stock in Lukoil, the second largest Russian oil company, British multinational Imperial Tobacco, Scottish bank HSBC and Canadian Oil Sands Ltd.
David Melton, executive director of the Illinois Campaign for Political Reform, said the amount of money Mr. Rauner has put into his campaign gives him an "unfair advantage" over opponents.
"It's just an indication of the growing role large dollar sums are having on politics and their potentially corrupting influence," Mr. Melton said.
Mr. Rauner is a founder of GTCR, a Chicago private equity firm that has invested some $10 billion in 200 companies since its inception in 1980, according to the firm's website.
Other big campaign donors in Illinois in this cycle include Richard and Elizabeth Uihlein, who have contributed $2.5 million to Republican candidates and conservative causes.
The Uihleins own Uline Inc., a large packaging supply company.
Liberal entrepreneur Fred Eychaner has put $794,000 into Democratic campaigns and political action committees so far in the 2014 cycle.