Bankrolled by Gov. Bruce Rauner, Illinois Republicans on Monday attacked Illinois House Speaker Michael Madigan by raising questions about the property tax appeals business handled by his law firm.

The bid to muddy up the powerful Democrat came in a television commercial running in the Chicago area and aimed at re-electing state Rep. Michael McAuliffe, the lone city Republican in the House. His district covers portions of the Northwest Side, as well as the suburbs of Niles, Des Plaines, Franklin Park, Park Ridge, Rosemont and Schiller Park.

The ad makes no mention of McAuliffe, instead linking his Democratic challenger, Merry Marwig, to Madigan. It’s a prime example of the financial prowess and real target of the state Republican Party this election cycle.

The state party wouldn’t disclose the price tag but called it “a major buy on broadcast TV in Chicago.”

McAuliffe’s race is shaping up to be one of the most expensive November statehouse races, and it is a financial proxy war being waged by Madigan and Rauner.

McAuliffe is one of four Republicans being targeted by Illinois Democrats this November. In turn, the House Republican Organization has contributed about $1 million to his political campaign fund.

Marwig, the daughter of a union laborer and an activist, is largely funded by unions and the state Democratic Party.

The new McAuliffe spot aims to boost him by demonizing Madigan, who wears three hats: speaker of the House, chairman of the Democratic Party of Illinois and partner in a law firm specializing in appealing property tax assessments. The spot asserts that Madigan’s tax work is responsible for “saving his friends millions, forcing you to pay more.” It claims Marwig got her property taxes lowered “at your expense.”

Illinois Republican Party spokesman Steven Yaffe said Madigan is being used in campaign ads because he’s “never been more unpopular” and because “far more people are able to hear our reform message this year than in past cycles.”

That’s because of a massive influx of cash for Republican candidates, in large part because of Rauner, who has contributed much of the $13 million raised by the GOP’s main campaign committee.

McAuliffe’s re-election bid is almost totally dependent on financial muscle from Rauner, House Republican Leader Jim Durkin, R-Western Springs, and the Illinois Republican Party.

Illinois Board of Election records reveal the flow of political money:

• On May 4, Citizens for Rauner transferred $5 million to the Illinois Republican Party.

• On May 6, the Illinois Republican Party transferred $2 million to Durkin’s House Republican Organization, the state House Republican political operation.

• On Sept. 6, the party sent another $1 million to the HRO.

• Over the summer and through Sept. 7, Citizens for Michael P. McAuliffe received more than $700,000 from the HRO, while the state GOP party in the past months has paid more than $60,000 for McAuliffe campaign staffers and other help. Citizens for Durkin, Durkin’s own political warchest, is kicking in money — at least $40,000 so far — for McAuliffe direct mail efforts.

Marwig, who created her campaign committee in February, is also tethered to Illinois Democrats for financial life support. In August and September, the Illinois Democratic Party paid more than $50,000 for postage and printing, and the Democratic Majority committee – the Democratic House political organization — paid $27,500 for polling.

Madigan spokesman Steve Brown on Monday called the Republican Party’s anti-Madigan ad “not surprising.”

“They’re doing everything they can to hold the twin anchor weight for Rauner and Trump around Michael McAuliffe’s neck. I don’t think this does it for him,” Brown said.

Brown said Madigan’s firm doesn’t give special treatment for clients, calling the insinuation “another one of those good, relationship-building cheap shots from the Rauner people.”

“They do it every two years. This year, they’re spending money on broadcast television in Chicago, which it just is, ‘If you give people a bigger piece of candy, they take bigger bites,'” Brown said.

In addition to McAuliffe’s race, state Democrats are targeting Rep. Dwight Kay of Glen Carbon; Avery Bourne of Raymond; and the seat vacated when state Rep. Ron Sandack, R-Downers Grove, abruptly resigned earlier this year. State Republicans are targeting the open seat of state Rep. Jack Franks, who left the Illinois House to run for McHenry County Board chairman; Rep. Mike Smiddy of Port Byron; John Bradley of Marion; and Kate Cloonen of Kankakee.

Contributing: Lynn Sweet