Periodically, I take notice of the impact of the foreclosure crisis on elections. When your former voters get forced out of their homes and scatter, it becomes that much harder to find them and motivate them to vote. Furthermore, the cost of sending out canvassers in high-foreclosure areas to walk precincts filled with vacant homes becomes steep. The time they spend trying to track down whether anyone lives in a particular home is basically time wasted.

Sasha Issenberg took notice of this a couple weeks ago, and I want to circle back to it, particularly today. One of the few polls that has shown movement toward Mitt Romney in recent weeks has been in Wisconsin. A poll there today found a dead heat, even though Obama received a convention bounce and pulled away in other battleground states like Ohio and Virginia.

This could be due to a late recognition by the Obama campaign that the state is competitive. It could be due to the presence of Wisconsin’s Paul Ryan on the ticket. It could be due to an RNC run by a former chairman of the Republican Party of Wisconsin, who seems more interested in flipping the state than winning the Presidential election. It could be due to the highly polarized nature of the state, coming out of the Scott Walker/union/recall wars. Or, it could have something to do with this:

New data from Milwaukee give an indication of how dire the Democrats’ disappearing-voter problem already is. This spring, the League of Young Voters, which was created to mobilize young minority communities, collaborated with the liberal Wisconsin Voices coalition to dispatch teams of young canvassers. Starting in April, they spent eight weeks knocking on 120,882 doors across 208 of Milwaukee’s 317 wards to raise awareness of the gubernatorial recall election scheduled for June. The doors had one thing in common: the voter file said they were all home to a registered voter whom a commercial data vendor had flagged as likely to be African-American.

But the voter file represented a fiction, or at least a reality that had rapidly become out of date. During those eight weeks, canvassers were able to successfully find and interact with only 31 percent of their targets. Twice that number were confirmed to no longer live at the address on file — either because a structure was abandoned or condemned, or if a current resident reported that the targeted voter no longer lived there.

This isn’t to say that 60 percent and above of Milwaukee’s black voters are gone, only that they can no longer be located at their last known address. That adds up to 160,000 African-American voters in Milwaukee, easily enough to put the state into one column or the other. This makes the voter file practically obsolete in Milwaukee, and means that you waste lots of time just finding voters through the trial and error of phone calls and voter contacts, rather than just making your pitch.

I submit that the 2010 House elections ended up more devastating for Democrats because of this phenomenon, particularly in states with foreclosure problems like Florida and Ohio. The impact on elections is perhaps the least important problem with mass foreclosures. But it symbolizes the massive disruption in people’s lives when they suddenly have to leave their home.