CHICAGO (AP) -- Voters in heavily Democratic Illinois go to the polls Tuesday for primary elections that will set the November slate for governor, U.S. Senate, several congressional districts and legislative seats.

Here are five things to know about election day in the state:

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1. GOP EYES GOVERNOR'S MANSION

Republicans will choose a nominee to take on Gov. Pat Quinn in what they see as their best opportunity to reclaim the Illinois governor's mansion after more than a decade of Democratic control. Quinn faces a little-known Democratic challenger and is widely expected to win Tuesday.

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2. ANOTHER SCOTT WALKER?

Venture capitalist Bruce Rauner of Winnetka, who praises the governorships of Wisconsin's Scott Walker and Indiana's Mitch Daniels, has been leading in polls against three veteran lawmakers, state Sens. Bill Brady of Bloomington and Kirk Dillard of Hinsdale, and state Treasurer Dan Rutherford of Chenoa.

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3. CROSSING OVER?

State employee unions have thrown their influence and money behind Dillard, trying to thwart Rauner, who vows to diminish the strength of what he calls government "union bosses." Dillard is asking union members and Democrats to cross over and pull GOP ballots.

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4. CHALLENGING DURBIN

Voters also will choose a Republican to take on Dick Durbin, the U.S. Senate's No. 2 Democrat. The race pits dairy magnate Jim Oberweis against businessman Doug Truax.

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5. AT THE POLLS

Voting stations are open from 6 a.m. to 7 p.m. Primary turnout traditionally has been low, but among new voters this year are 17-year-olds who will turn 18 before the November election.

-- Associated Press