11/02/2010 01:13 pm ET | Updated May 25, 2011

Illinois State House, Senate In The Balance: Important Down-Ballot Races

Illinois is in a unique position this year to have a major say in the balance of power in the U.S. Congress. With five contested House races and a neck-and-neck Senate race, both parties are looking to Illinois as vital to winning legislative majorities.

But a little further down the ticket, some important races are playing out at the local and state level that could determine the make-up of county government and the state legislature in Springfield.

HuffPost Chicago highlights five of the closest and most compelling down-ticket races in the Chicago area. Taken all together, the outcomes of these races will show the strength of the Democratic machine, and measure the size of the Republican tide in the state.

County Assessor: Joe Berrios (D) vs. Forrest Claypool (I) (Cook)

The "biggest little race" on the ballot this cycle is the battle for Assessor, the post that sets the value of nearly every property in Cook County to determine property tax rates. Claypool and the news media have accused Berrios of engaging in "pay-to-play" while at the Board of Review, which looks at appeals of decisions made by the Assessor. They say Berrios took campaign donations from tax appeals lawyers and gave their clients tax breaks in return.

Berrios says that Claypool is one to talk about donors, citing the many very wealthy contributors that have financed his opponent's campaign. He is running on the strength of the Democratic brand, and portraying himself as a populist alternative to Claypool, who he paints as an elite lakefront liberal.

The two men have spent millions of dollars in the normally obscure race, and it has become one of today's most closely watched local races.

State Senate: John Mulroe (D) vs. Brian Doherty (R) (Portage Park, Harwood Heights, Norridge)

It's rare that a Republican has a snowball's chance in a state legislative race in Chicago. But this is a rare year for Republicans. Alderman Brian Doherty has long been the only Republican on the Chicago City Council; now he's hoping to take the show to Springfield. But his experience on the City Council is cutting both ways, as his Democratic opponent has repeatedly tarred him for voting for the unpopular parking meter lease. Mulroe also accused Doherty of using his aldermanic office to campaign for State Senate, which is illegal.

Both sides see this open Senate seat as critical to control of the chamber. If Republicans want a shot at the Senate -- which most observers see as unlikely, but hey -- they'll need to run the table in races like this. Likewise, if Democrats don't want their 37-22 majority to shrink too badly, they'll want a convincing hold here in the Northwest Side.

State House: Hamilton Chang (R) vs. Daniel Biss (D) (Evanston)

The State House, on the other hand, is a chamber that might really be up for grabs. Republicans need to pick up twelve seats, and are playing aggressively across the state. In fact, Minority Leader Tom Cross says the 17th District is the only race in the state where they're on the defensive.

Republican Rep. Beth Coulson left the seat to launch an unsuccessful bid for U.S. Congress (she lost in the primary to Bob Dold). Daniel Biss ran an upstart challenge to the six-term-incumbent Coulson in 2008, coming within 1,600 votes of a win, and is hoping to keep the momentum up against his new Republican opponent Hamilton Chang, a financial advisor to nonprofits. Both are qualified, moderate, and reform-minded.

State House: Ryan Higgins (R) vs. Michelle Mussman (D) (Schaumburg)

The political inclinations of the 56th district are somewhat murky. In 2006, it elected Republican Paul Froehlich, who was running unopposed. Two years later, it elected Democrat Paul Froehlich by 6,000 votes -- the representative had changed parties in the interim.

Now, Froehlich isn't running, so it's between Higgins, a knowledgeable and commanding healthcare attorney, and Mussman, a self-described "mom on a mission" and community activist. Higgins picked up some valuable endorsements, but Mussman continues to fight on the streets. This race promises to be a close one.

State House: Toni Berrios (D) vs. Jeremy Karpen (G) (Logan Square, Avondale, Belmont-Cragin)

Another Berrios is also running a tight race. Toni, a four-term incumbent and the daughter of Joe, is facing a challenge from Jeremy Karpen, a Green Party candidate who took 21% of the vote against her in 2008. On the surface, Karpen seems like an unlikely prospect, given that Berrios has an enormous campaign war chest and machine backing. But Karpen's ground game has been much more active than his opponent's, and this may be one year in which the Berrios name does Toni more harm than good.

If Karpen were to pull off the upset, it would be a historic win: he'd be the first Green Party state legislator in Illinois history, and -- barring a similar surprise elsewhere -- the only one in the United States.