State Sen. Darren Bailey won last night's GOP primary handily and will take on incumbent Gov. J.B. Pritzker in November.

Why it matters: The contentious race was the most expensive primary in Illinois history, with billionaires Ken Griffin, Dick Uihlein, Pritzker and former President Donald Trump all weighing in.

• The campaigns spent a combined $216 million, which some analysts believe is just the start of the most expensive nonpresidential campaign in U.S. history.

The intrigue: Both Trump and Pritzker seemed to want a Bailey win, but for different reasons.

• Trump's nod seemed to be inspired by Bailey's conservative views and a shared penchant for dissing Chicago.
• Pritzker, meanwhile, backed ads calling Bailey "too conservative for Illinois," which may have rallied conservative voters.
• "I think it's obvious Gov. Pritzker thinks I'm the easiest candidate to beat, and my message to Gov. Pritzker is, 'Be careful what you wish for, because it's coming right toward you,'" Bailey said in a recent debate.

The big picture: Trump's last-minute endorsement gave Bailey a big victory in a state that has largely backed moderate GOP candidates.

Between the lines: The outcome signals a humiliating loss for billionaire Ken Griffin, who spent more than $50 million supporting third-place finisher Richard Irvin.

• Griffin's donations also supported other statewide candidates who lost, including Steve Kim (for attorney general) and John Milhiser (for secretary of state).

The other side: Pritzker and the Democratic Governors Association spent $30 million to run ads against Bailey and others in the GOP primary.

• "Darren Bailey is a MAGA extremist who's threatening to drag Illinois backwards," DGA executive director Noam Lee said in a statement. "There is no doubt Illinois will reject him and his dangerous agenda this November."

Former state Treasurer Alexi Giannoulias is representing Democrats in the race for secretary of state.

Why it matters: The position was held by Jesse White for 23 years and was previously seen as a potential launching pad to higher office.

Between the lines: Giannoulias, who won the election by double digits, raised the most money and beat back Chicago City Clerk Anna Valencia.

• Valencia was endorsed by several state leaders, including Sen. Dick Durbin and Gov. Pritzker, as well as White.
• She was also endorsed by Planned Parenthood of Illinois.

What we're watching: The race was marred by attack ads from each side questioning the other's ethics, which could follow Giannoulias into the general election.

The other side: Bloomington state Rep. Dan Brady defeated former U.S. Attorney John Milhiser.

• The last time the GOP won this office? 1994.

What's next: Giannoulias vs. Brady in November.

• Voter turnout was exceptionally low. (ABC 7)
• Rep. Danny Davis narrowly held on to his seat after a tough race against progressive challenger Kina Collins. (NBC 5)
• Attorney Kathy Salvi (GOP) will face incumbent Sen. Tammy Duckworth. (Daily Herald)
• Jonathan Jackson, son of Rev. Jesse Jackson, won the Democratic primary in the 1st District. (Block Club)
• Progressive candidate Delia Ramirez won the Democratic primary in the 3rd District. She was endorsed by Rep. Chuy Garcia. (NBC 5)
• Incumbent Cook County Assessor Fritz Kaegi defeated Kari Steele. (Sun-Times)

Rep. Mary Miller won Illinois' GOP primary for the 15th Congressional District after fellow House Rep. Rodney Davis conceded the race.

The big picture: Miller's victory demonstrates the power of a Trump bump, even for a controversial candidate without strong local party backing.

Why it matters: This intraparty race between two conservative incumbents was one of the state's most closely watched matchups.

• It was seen as a test of former President Trump's influence in the area.
• And it attracted $11.5 million in outside spending, according to Politico.

Between the lines: Miller, a member of the House Freedom Caucus, had to overcome some notable public gaffes.

• She infamously told a Washington crowd in January 2021 that "Hitler was right on one thing."
• And last week, she called the Roe v. Wade repeal "a victory for white life," later saying she meant "right to life."

The intrigue: Davis co-chaired Trump's Illinois campaign in 2020 and even used pictures of the former president in his ads.

• But the congressman also voted to certify President Joe Biden's electoral victory and supported a commission to investigate the Jan. 6 insurrection, two points Miller was quick to highlight.

What's next: Miller will face Democrat Paul Lange for the seat in this largely conservative district.

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Rep. Sean Casten won the contentious Democratic primary against fellow House Rep. Marie Newman.

Why it matters: After Illinois lost a congressional seat, the two incumbent Democrats ran against each other. Though both are progressive and share many of the same stances on guns and climate, Casten has been seen as a more moderate candidate with a better chance to win this formerly Republican-held district.

Between the lines: Newman represents the 3rd District, but much of it was carved into the 6th.

• The 6th includes parts of the Chicago suburbs, like Downers Grove, but was remapped to take over parts of the 3rd in southwestern Cook County.
• Carving Newman's 3rd District seemed to telegraph disrespect from Democratic party leaders in charge of the new map.

Of note: The race was extremely acrimonious.

• Newman faced allegations that she'd bribed a potential primary challenger with a job offer and is under investigation by the Office of Congressional Ethics, though she has denied any wrongdoing.