(CNN)The Land of Lincoln heads to the polls today for its primary, the second state to hold a primary this year for the 2018 midterms. While four congressional districts are ranked on CNN's Key Races, the one major House race to watch tonight is a Democratic primary that's turned some of the party's biggest leaders and outside supporters against each other.
Here's what you need to know:
- Seven-term Democratic Congressman Dan Lipinski, a conservative Democrat who ran for the seat when his father retired in 2004, could meet his match by a political newcomer, Marie Newman, whose more liberal views and major endorsements made big waves in a race in which he ran opposed just two years ago.
- Democrats are also in a tough race for the gubernatorial nomination to take on Republican incumbent Bruce Rauner, who is considered to be among the most vulnerable among GOP governors this fall. Tonight's winner will have one of the best chances to flip a governor's seat in the country.
- There are no mandatory recount laws in Illinois. A candidate who is within five points of the top vote leader may request a non-binding recount in up to 25% of precincts. Further actions can be taken after the votes are counted.