(CNN) – Illinois voters head to the polls Tuesday in primary balloting for virtually all statewide offices, including Republican races to see who will face off against the state's Democratic governor, who's considered vulnerable, and against Sen. Dick Durbin, the number two Democrat in the U.S. Senate.
President Barack Obama's home state tilts reliably blue in presidential elections; He won 57% in 2012. But Democratic Gov. Pat Quinn's ailing approval rating makes him vulnerable and could open up that seat to Republicans come November.
Republicans will also seek inroads in Congress, including one race that is competitive between Democrats and Republicans.
Here's what to watch for in Tuesday balloting:
GOP gubernatorial contest
Republicans see takeover potential here as Quinn is considered one of the most vulnerable Democratic governors up for reelection.
He is seeking his second full term after taking over for former Gov. Rod Blagojevich in 2010. Quinn is expected to win the primary against community organizer Tio Hardiman, but a substantial victory margin against the relatively unknown candidate is important for his momentum heading into the general election.
The four Republican candidates vying to replace him have focused a lot on hitting Quinn over high unemployment and taxes in the state.
Millionaire businessman Bruce Rauner, a first-time candidate from the wealthy suburb of Winnetka on Chicago's North Shore, has outspent his GOP opponents and is seen as the frontrunner. He faces three state lawmakers; Sens. Bill Brady and Kirk Dillard, and State Treasurer Dan Rutherford.
Quinn narrowly beat Brady in 2010 when he was the GOP gubernatorial nominee.
Race for IL-13
The competitive race for Illinois's 13th Congressional District, an area that covers the southwest suburbs of Chicago and makes up a stretch of the central portion of the state, has garnered national attention politically.
Incumbent Republican Rep. Rodney Davis narrowly beat his Democratic opponent in 2012. His main challenge Tuesday will come from lawyer and former Miss America Erika Harold. She gained national attention as a speaker at the Conservative Political Action Conference this month but her bid is still considered a long shot.
The Democratic Congressional Campaign Committee has put its money behind former Madison County Judge Ann Callis for the 13th District race. Callis will face off against college professor George Gollin and social policy analyst David Green.
Durbin to get a Republican challenger
Two Republicans hoping to unseat Sen. Dick Durbin, will duke it out on Tuesday.
State Sen. Jim Oberweis came under fire from challenger Doug Truax, a businessman and West Point graduate, for an "unprecedented weeklong vacation in Florida" days before the primary, calling Oberweis a "timid snowbird." Oberweis, who owns a residence in Florida, said he was in the state to celebrate his wife's birthday.
Durbin, who is unopposed in his primary, won 68% of the vote in his 2008 re-election victory against a little-known GOP opponent.