illinois polls
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:

Polls are open 7 a.m. to 8 p.m. EDT

  • 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.

Here’s a closer look at what to watch tonight (and after):

Fight for the soul of the Democratic Party: Lipinski is a conservative Democrat who is against abortion, voted against Obamacare and sponsored the Religious Freedom Act, a bill strongly opposed by the LGBTQ community. He’s been an ally of the unions and has long sat on the House Transportation and Infrastructure Committee, an important role for his district, which harbors Midway International Airport. He’s been a staple among “Blue Dog” moderate Democrats, who have found themselves at odds with a party that has swung more to the left. A loss for Lipinski against Newman will say a lot about how the Democratic Party views its more conservative members.

Which establishment rules? Sens. Bernie Sanders and Kirsten Gillibrand joined NARAL, Planned Parenthood, EMILY’s List, the Human Rights Campaign and Illinois Democratic Reps. Schakowsky and Gutierrez in supporting Newman for Congress. Lipinski took in the support of the Illinois AFL-CIO, Illinois AFSCME, dozens of local mayors, House Democratic leader Nancy Pelosi, the Chicago Tribune and Sun-Times. The winning candidate will show which side of the party has the most strength right now.

Holocaust denier on the ballot: The Republican running for the 3rd Congressional District’s nomination is Arthur Jones, a Holocaust denier with a history of anti-Semitic comments. Though many Republicans might not support him, he is running unchallenged in this district Hillary Clinton won with 15 points in 2016. This is considered a safe Democratic district, so it’s unlikely he will win in the general election. Still, come 8pm ET tonight, Jones will be the official GOP nominee.

Money, money, money: With over $150 million raised so far, the gubernatorial race here could end up as one the most expensive governor races in history. Rauner, a millionaire former businessman, could end up facing billionaire J.B. Pritzker, should he win tonight’s Democratic primary. A fight between these two would end up costing both a lot of their own personal money. The current record is the $280 million spent in California’s 2010 race between Democrat Jerry Brown and Republican Meg Whitman, a record this race could easily surpass.

CNN’s Annie Grayer and Eric Bradner contributed to this report.