Now that Congressman Jackson has resigned his congressional seat it's up to Governor Quinn to call for a special election to replace the congressman, and one plausible scenario would have the special primary in late February with the special general in early April.
The special election will almost certainly be decided during the special primary as the district leans so overwhelmingly Democratic that it is very unlikely that the Democratic nominee would lose the general election. Even the much maligned Jesse Jackson Jr. won re-election in this district with 63% of the vote in 2012 in a year where he was surrounded by a media firestorm and was too ill to campaign in any meaningful way, so it's difficult to envision a plausible scenario where this district is won by anyone other than a Democrat.
The district is geographically large, at least for a Chicago based district, encompassing some of the south side of Chicago, the southeastern part of Cook County, the eastern part of Will County and all of Kankakee County. However the population density of the Democratic Primary electorate leans heavily towards the Cook County portion of the district. Here is the distribution of Democratic Primary voters from 2012, I've separated Cook County into Chicago and Cook Suburbs even though they are both within Cook County:
|County/Area||Total||% of Total|
As you can see about a third of the Democratic Primary vote came from Chicago, about 55% from the Cook County suburbs and then only a little less than 6% from each of Will and Kankakee counties. Here's the same data but broken out by ward/township (I didn't bother breaking out the data for Kankakee since the total is so small):
|County||Township||Total||% of Total|
Vote rich townships like Thornton, Rich and Bloom along with Wards 7 & 9 stand out as possible areas of candidate vote strength. However all of this data is based on the primary electorate in 2012 which featured a reasonably high profile race between incumbent Congressman Jesse Jackson Jr. and former Congresswoman Debbie Halvorson. It is very much uncertain what voters may turn out for a special primary election this winter and predicting what that electorate will look like and who will turn out will be a difficult challenge. That challenge makes polling difficult and also direct mail potentially inefficient and unnecessarily expensive for those who get it wrong. It's likely that the candidate that emerges successful will have an experienced team who were able to accurately capture the likely electorate.
There are a great many rumored candidates, see below for a partial list. Here's a very handy tool I've developed that will allow you to see not only the 2nd Congressional District boundaries in great detail but also the boundaries (past and present) for the districts many of these candidates have represented or run in before. As you can see some candidates only partially shared voters with the voters of IL-02 while others have represented large portions of this district and would benefit from a built in name ID among voters. Here's a partial list of potential candidates, see this piece from the Sun-Times' Mark Brown for more opinionated and in depth analysis:
All of this district lies within the Chicago media market so it seems that broadcast television advertising for this race will probably be prohibitively expensive unless some candidate(s) really excel at fundraising. The more plausible scenario is that the most flush candidates could end up on cable television. Here's the Comcast coverage map for their regional cable markets in the Chicagoland area. Unfortunately their map is rather small and difficult to read but you can see that a candidate in this district would only need to buy just a few regions.