Mike Quigley released his first TV ad today, which touts his efforts to "take on" Cook County President Todd Stroger:

Capitol Fax reports that the ad buy behind this spot "is said to be slightly smaller than Rep. John Fritchey’s purchase, which was around $120,000."

Meanwhile, at our request, Everyblock's Paul Smith has provided us with some useful info on which of the four elected officials running in this race -- Reps. Sara Feigenholtz and John Fritchey, Ald. Pat O'Connor, and Quigley -- has the largest native constiuency in the 5th Congressional District.  Smith created an interactive map that tallies the geographic percentages represented by each of these lawmakers' overlapping districts or wards.  (We're hoping to eventually get population-based estimates as well.)

Of the four, Quigley's district has the largest overlap, covering 11.1 percent of the 5th District:

Fritchey's state legislative district is almost entirely inside the 5th District, where it covers 9.3 percent of the entire area:

O'Connor's ward covers 3.8 percent of the congressional district:  

And to the north, 3.5 percent of the 5th District overlaps with Feigenholtz's state legislative district:

This is just one of many factors, including fundraising, advertising exposure, and, last but not least, field operations.  But it can't hurt to have a large constituency that has voted for you in previous elections.

Finally, Feigenholtz received the endorsement of the United Auto Workers Illinois State Community Action Program today:

"Like most voters, UAW members want a candidate who has risen above political gamesmanship to gets things done and has a strong record and commitment to health care and restoring the economy," said Dennis Williams, Region Four Director for UAW. "The UAW is proud to throw our support behind Sara Feigenholtz because she has a proven and deep commitment to improving the lives of working men and women."

Full disclosure: The SEIU Illinois Council -- which is the sole sponsor of Progress Illinois -- has endorsed Sara Feigenholtz in the 5th Congressional District race. Progress Illinois will not be endorsing any candidate in this race.