Progress Illinois rounds up some key state races to watch in Tuesday's election.
From the heated U.S. Senate race to the expensive state comptroller contest, Illinois features many key battles to watch this election.
Tuesday's general election also includes the high-profile "tossup" race in Illinois' 10th congressional district, plus several hotly contested state House and Senate contests that will determine whether Illinois Democrats retain their supermajorities in both chambers.
Here's a look at some of the key races:
The race between incumbent U.S. Sen. Mark Kirk (R-IL) and Democratic challenger Tammy Duckworth could prove crucial in determining which party controls the U.S. Senate.
The Cook Political Report rates the Illinois U.S. Senate race as leaning Democratic.
Kirk, a Republican who describes himself as fiscally conservative and socially moderate, was first elected to the U.S. Senate in 2010. He had a stroke in January 2012 and returned to Congress one year later.
Duckworth, an Iraq War veteran who was wounded in combat and lost both legs, is a U.S. congresswoman. She has represented Illinois' 8th congressional district since 2013.
Kirk, who claims to be an independent voice in the U.S. Senate, has broken Republican ranks by meeting with Merrick Garland, President Barack Obama's Supreme Court nominee, and withdrawing his support for GOP Presidential candidate Donald Trump.
Kirk has raised eyebrows for making various gaffes and controversial comments. More recently, Kirk faced criticism for remarks he made about Duckworth's family military history, for which he later apologized. The comments, which some have described as "racist," resulted in Kirk losing two key endorsements from the Human Rights Campaign and Americans for Responsible Solutions PAC.
During the campaign, Kirk has hammered Duckworth on Veterans Affairs issues, while Duckworth has criticized Kirk for previously inflating his military record.
The race to succeed Duckworth in the 8th congressional district, which covers Chicago's west and northwest suburbs, pits Republican Peter DiCianni against Democrat Raja Krishnamoorthi.
Check out WTTW's recent candidate forum with DiCianni and Krishnamoorthi here.
10th Congressional District:
Political observers consider the 10th district battle between incumbent Republican Bob Dold and Democratic challenger Brad Schneider to be a tossup.
This year marks the third consecutive race between Dold and Schneider, the former 10th district representative.
In 2012, Schneider defeated Dold, unseating the then-freshman incumbent. Dold regained his seat from Schneider in 2014.
The district includes a large swath of Lake County and the northern portion of Cook County along Lake Michigan.
The Illinois comptroller race between incumbent Republican Leslie Munger and Democratic challenger Susana Mendoza, who is currently Chicago's City Clerk, has been the most expensive state contest this election cycle.
More than $12 million has reportedly been spent on the race.
Contribution limits were busted in the race in late September after Munger's campaign received a $260,000 loan from her husband. The caps on campaign contributions can be removed in the comptroller's race if a candidate gets a donation of at least $250,000.
The Munger v. Mendoza race is seen by many as a proxy war between longtime Democratic House Speaker Michael Madigan and Rauner, the state's first Republican governor in over a decade.
Rauner appointed Munger to the comptroller post after the December 2014 death of Republican Comptroller Judy Baar Topinka.
20th House District
The 20th House district race is another Rauner-Madigan proxy battle. Incumbent Rep. Mike McAuliffe (R-Chicago) is facing Democratic opponent Merry Marwig.
McAuliffe, the sole Chicago Republican in the state legislature, was first elected to the House in 1996.
Nearly $4.6 million has poured into the 20th House district race, making it the most expensive state legislative contest this cycle, according to the Chicago Tribune.
79th House District
Another high-profile and expensive race is in Illinois' 79th House district.
Incumbent Rep. Kate Cloonen (D-Kankakee), a state representative since 2013, is being challenged by Republican attorney Lindsay Parkhurst.
Allegations of voter fraud and intimidation have swirled in Kankakee County.
In October, Kankakee County State's Attorney Jamie Boyd announced an investigation into alleged voter fraud, saying the probe was prompted by "reports of individuals from Chicago offering gifts to potential voters in exchange for a vote for Kate Cloonen, Hillary Clinton and others." Boyd said "several" vote-by-mail requests may have also been "fraudulently executed."
For their part, Kankakee government officials have faced voter intimidation accusations.
Illinois Attorney General Lisa Madigan, U.S. Attorney James A. Lewis and Illinois State Board of Elections officials met last month with the Kankakee County state's attorney and a representative from the local clerk's office.
Madigan's office said the meeting was held "to ensure a fair, open and legal election this fall that allows all residents to vote equally without obstacles or intimidation by law enforcement officials or offers in exchange for votes, all of which are prohibited by law."
117th House District
Incumbent Rep. John Bradley (D-Marion) is facing Republican businessman Dave Severin in the 117th House district race. Since 2003, Bradley has represented the southern Illinois district, which covers the communities of Benton, Marion, West Frankfort and others.
Illinois Republicans are targeting Bradley and at least two other southern Illinois Democrats, including Sen. Gary Forby (D-Benton) and Rep. Brandon Phelps (D-Harrisburg), this election cycle.
49th Senate District
The state's 49th Senate district race is among those in which contribution limits have been lifted.
Funding caps can be lifted in legislative races if a super PAC spends at least $100,000 on the race. The Liberty Principles PAC triggered that threshold with its contributions spent on behalf of Republican challenger Michelle Smith.
Smith is challenging incumbent state Sen. Jennifer Bertino-Tarrant, a Democrat from Shorewood.
The district also includes portions of Oswego, Plainfield, Crest Hill and other communities.
Other Illinois legislative races to watch include the 23rd Senate district contest between incumbent Sen. Tom Cullerton (D-Villa Park) and Republican Seth Lewis; the rematch in the 62nd House district between incumbent Rep. Sam Yingling (D-Grayslake) and Republican Rod Drobinski; the 76th district battle between Andrew Skoog (D-Spring Valley) and Jerry Long; and the 112th House district race between incumbent Dwight Kay, (R-Glen Carbon) and Democrat Katie Stuart, among others.
In Cook County, the race for state's attorney is also noteworthy. Democrat Kim Foxx is up against Republican Christopher Pfannkuche.
Foxx soundly defeated Cook County State's Attorney Anita Alvarez in the March Democratic primary. Leading up to the primary, Alvarez faced fierce public criticism, and calls for her resignation, for her handling of several law enforcement cases, including the fatal shooting of 17-year-old Laquan McDonald by Chicago police officer Jason Van Dyke.