It's Election Day in Illinois! Polls are open in a Chicago-area district where voters will select their nominees in the special election to replace former congressman Jesse Jackson Jr., who resigned last year and admitted last week to misusing hundreds of thousands of dollars in campaign funds.

Can Robin Kelly (right) win what has been an unpredictable campaign? Can Robin Kelly (right) win what has been an unpredictable campaign? (M. Spencer Green/AP)

What really matters today is the Democratic primary. Given the district's heavy Democratic tilt, the party's nominee may as well be considered the next member of Congress. Below are four questions to bear in mind as you watch the returns come in this evening. And stay tuned to Post Politics tonight for results, some time after the polls close at 8 p.m. ET.

1) Did Bloomberg's PAC propel Robin Kelly over the top on the issue of guns? New York City Mayor Michael Bloomberg's super PAC poured about $2.5 million (!) into the campaign in an effort to defeat former congresswoman Debbie Halvorson and boost former state representative Robin Kelly. (For a more detailed look at where the money has gone, check out this New York Times rundown). The general consensus heading into today is that Kelly is now ahead of the pack in the frontrunning position.

Bloomberg's group has sought to remind voters about the high marks Halvorson has received in the past from the National Rifle Association, and the race has unfolded against the backdrop of a city plagued by gun violence.

If Kelly wins today -- it's worth remembering that polling has been all over the place -- it will serve as a strong message to both Democratic and Republican candidates that the NRA is not the only group in the gun debate that can influence a campaign and that Bloomberg's PAC will continue to be a strong counterweight to the nation's largest gun-rights group. If Halvorson survives -- her high name ID and the fact that she is a white candidate in a field with many African American candidates who may split the black vote gives her a chance -- it will be a setback to Bloomberg and gun control advocates.

2) How will the weather affect turnout? The Chicago area could get up to 6 inches of snow in a winter storm today. That could depress turnout -- which wasn't expected to be high in the first place, considering this is an off-year, winter special House primary election.

This is Chicagoland, a area that is used to inclement weather. And the campaigns say they are prepared. But in a race with a packed field, the candidate with the most passionate supporters and best turnout operation will be very well-positioned today.

3) What about Anthony Beale? Most of the attention in ths race has gone to Kelly and Halvorson the past couple of weeks. But a third candidate, Alderman Anthony Beale, is worth keeping an eye on as returns come in tonight. If Beale does better than expected, it's likely bad news for Kelly and good news for Halvorson.

One of the reasons Halvorson looked like an early favorite in this race -- that is, before Bloomberg's PAC came in and barraged her over the airwaves -- was the potential for the black vote to be split among the field's many black candidates. State Sen. Toi Hutchinson's decision to drop out of the race and endorse Kelly was a boon to Kelly's chances. But Beale's presence in the race remains a complicating factor for her.

4) What will turnout look like inside and outside of Chicago? Halvorson's base is the part of the the district that lies well south of the city (she did well in Will and Kankakee Counties in 2008), an area she represented in Congress. The higher turnout is there, there better her odds will be. Kelly and Beale will be more reliant on votes in and around Chicago (Cook County).

Daily Kos Elections has a good map, where you can get a better sense of the district's layout.