* John Tillman of the Illinois Policy Institute writes…

When a GOP candidate hits 20 percent of the vote in Chicago, the math is such that they will almost always win so long as they don’t massively underperform elsewhere.

Tillman uses this stat to show that Bill Brady could’ve won in 2010 had he done better in Chicago.

* But a look at the numbers shows it’s just not that simple. Bill Brady won 17.41 percent of the city vote in 2010. But Republican Mark Kirk took 19.47 percent of Chicago’s total.

However, the difference in the two totals was just 13,971 votes (134,081 minus 120,110). Brady lost to Quinn by 31,834 votes statewide. Kirk beat Alexi Giannoulias by 59,220 votes statewide. Winning 20 percent of the city’s vote wouldn’t have made up for Brady’s other problems.

* The difference? Partly in Kirk’s congressional district, where he was much better known. Kirk outpolled Brady by 27,773 votes in suburban Cook County. Kirk did better than Brady in Lake County by 12,296 votes.

But Kirk did better than Brady in every suburban county. If you include suburban Cook, Kirk outpolled Brady by 56,184 suburban votes. Exclude Cook, and Kirk received 28,411 more suburban votes than Brady. There’s your election.

The bottom line here is that the Republicans had better field a candidate who can perform well in the suburbs. And that’s where ideology comes into play.

…Adding… From Tillman…

Hi, Rich,

Read your post and I actually don’t disagree with your points but I do disagree with how you characterize my point.

You pull this line I wrote:

“When a GOP candidate hits 20 percent of the vote in Chicago, the math is such that they will almost always win so long as they don’t massively under perform elsewhere.

And then you wrote:

“Tillman uses this stat to show that Bill Brady could’ve won in 2010 had he done better in Chicago.”

I did not say that. My point was clear: That a GOP nominee cannot “massively underperform elsewhere” but hitting at least 20% is a starting point. Brady did under perform relative to Kirk, as you rightly point out, in the suburbs (in terms of percent of the vote) and downstate (in terms of generating turnout).

John