CHICAGO (CBS) – Republican Gov. Bruce Rauner on Monday called for Cook County Assessor Joe Berrios to resign.

CBS 2’s Derrick Blakley reports, Rauner took aim at Berrios over the county’s property tax assessment system.

“This system has to change,” he said. “Joe has to go.”

Michael and Marianne Murphy insist their modest Wheeling home shows there is something rotten about Cook County’s taxes.

“Our assessed value has gone down 25 percent, and in the last 10 years, our property taxes have increased 50 percent. There is something wrong with that math,” Marianne Murphy said.

Berrios also heads the local Democratic Party. He is allied with Illinois House Speaker Mike Madigan, who has made millions appealing property taxes for downtown high-rises.

Berrios is backing the Democratic front-runner for governor, J.B. Pritzker, which may be why Pritzker isn’t calling for Berrios to step down.

“I think it’s important for the voters of Cook County to make the decision about who they want in that position,” Prizker said. “I don’t think it’s my job to foment a war between Democrats.”

It is too late for that.

Prizker’s Dem rival, Chris Kennedy, has already called for Berrios to resign, blasting Pritzker in the process.

“J.B. has been a tax cheat as well,” Kennedy said. “You look at what he did on Astor Street. If that’s not tax cheating, I don’t know what is.”

Prizker managed to wrangle a nearly $250,000 tax break from Berrios’ office by leaving his Astor Street Gold Coast mansion in disrepair.

For his part, Rauner on Monday insisted that he has never sought a property tax break.

However, sources tell CBS 2, tax records show in 2012 and 2015, Rauner had assessments lowered on two Chicago condos.

Meantime, Berrios responded to Rauner’s demand by saying the governor should resign.