Well, so much for Scott Walker's brand of Republicanism being all about forward-looking, green-eyeshade bottom-line reform. It's flown mostly under the national radar this week, but Walker decided to go old-school, late-1980s-style, with a TV ad conjuring the menace of inner-city crime to attack his opponent, Milwaukee Mayor Tom Barrett. It seems awfully anachronistic to be going this route in an era of falling crime, when voters are far more concerned about layoffs than muggings.

But I can't help but wonder whether it might be more effective in Wisconsin, given the state's unusual circumstances, as captured so well in Jason DeParle's classic book on welfare reform, American Dream. What sets Milwaukee apart from other northern industrial cities like Chicago, Detroit, and Philadelphia is that the Great Migration of blacks from the South got to Milwaukee late. In 1950, after several decades of black migration to other Northern cities, Milwaukee's black population was still well below 10 percent. It was only in the decades that followed that large numbers of blacks flowed into the city, often from Chicago. One result of this is that metropolitan Milwaukee has lagged behind the demographic trends of other northern cities. White flight happened later in Milwaukee than elsewhere; and so has the shift toward more integrated inner suburbs that you've seen in cities. This helps explain why the suburbs of Chicago, Philadelphia, Detroit, New York, St. Louis, Baltimore, Washington etc. flipped to blue in the past decade or two, whereas the suburbs of Milwaukee remain largely a Republican stronghold. Politically, suburban Milwaukee today arguably resembles suburban Chicago of 1990 more than it does suburban Chicago of today. It's a land of rabid right-wing talk radio, it's Scott Walker's base, and it's not un-receptive to scary stories from the dread inner city next door.

It's worth noting that Barrett has not taken this attack lying down. In Thursday night's debate, he went after Walker over the ad:

“He’s running a commercial right now that shows a dead baby. He shows a picture of a dead baby. This is Willie Horton stuff,” an exasperated Barrett charged during the one-hour debate at Marquette University. “You should be ashamed of that commercial Scott Walker."....

Barrett’s outrage at the scathing spot created the most emotionally charged moment of the evening.

“That baby died. The person who killed that baby was arrested by Milwaukee police, was prosecuted by Milwaukee … But you know what they did wrong. After the baby died, they didn’t change the code. It was a bureaucratic mistake,” Barrett explained in front of a live audience. “And you’re running a commercial attacking my integrity, claiming that I had something to do with this, and you know that’s false. I’ll tell you right now, I had nothing to do with that.”

Keep an eye on this. How Wisconsin -- the land of admirable good-government ideals but also of some unpleasantly behind the times racial dynamics -- responds to this last-minute attack could well help decide Tuesday's big vote.

Follow me on Twitter @AlecMacGillis