(CNN) A billionaire, a Kennedy and an upstart state lawmaker are the leading Democratic challengers in the race to unseat Republican Illinois Gov. Bruce Rauner.

The Land of Lincoln, which heads to the polls on Tuesday, has been home to one of the most intense primary run-ins of the midterm cycle, with J.B. Pritzker, heir to the Hyatt hotel riches, in the lead, state Sen. Daniel Biss trying to outflank him on the left and Chris Kennedy, a businessman who's the son of the late Robert F. Kennedy, hoping for a late surge after a campaign that's run hot and cold.

Rauner is also facing his own primary challenge from the right by state Rep. Jeanne Ives, who has attacked him for not pursuing a more ambitious conservative social agenda and, like the Democrats, what they view as general incompetence in handling the state's dire financial situation, which included a more than two-year-long budget impasse ending last year.

Democratic primary turns nasty

On the Democratic side, Pritzker has plowed about $70 million of his own money into his campaign, and will enter primary day as a favorite, even as the specter of undecided voters -- which recent polling has shown could be enough to swing the race -- leaves open the potential for a late upset.

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