You can fill out a change of address form any time prior to (and probably even on) election day. The details can vary from precinct to precinct, I believe. However, who's going to know that?

This is one of those tactics that might not work in their favor, however. I'm not sure that the majority of foreclosed people are Democrats. (Of course, after being foreclosed their position on certain issues might change.) The very poor and/or those living in urban settings often don't have houses to be foreclosed on, after all.

Vote? You don't need no stinking vote!
There has been a policy in the US to deny the voting right to blacks since they got the vote. Much like slavery was continued by chain gangs, the laws were changed to deny felons the right to vote. Blacks were rounded up and jailed for minor offenses, sent off to build roads and public work projects. They couldn't vote in prison. And if they got out they were denied the right to vote. So much for forgiving someone who has paid their "debt to society." Racist legislatures wrote laws that discriminated against blacks. They still do.
In the 2000 election, Florida expanded the policy by denying voting rights to citizens from democratic leaning districts who were "suspected" of being ineligible to vote; based on computer generated data mining reports. Black soldiers in Iraq and Afghanistan were denied their right to vote by the illegal caging scam. (Which Bush and the JustUs Department made legal) And now Michigan is at it. So is my state, sad to say. With a Democrat governor in charge, in a Democratic primary no less, Native American and Hispanic voters in this year's primary election were forced to vote with provisional ballots at a much higher rate than Anglos, and voting machines were limited to force long waits in their districts. It took weeks for the totals to be posted.
The obvious conclusion is that many people who speak to the fundamental democratic principle of one vote per person are lying by their actions. Along with the traditional exclusion of Blacks, and the more recent discrimination against Native Americans and Hispanics, they still don't want working people to vote, so they schedule elections on Tuesdays during working hours, instead of Saturdays. The list goes on: provisional ballots, voter ID, too few voting machines in certain districts, hackable paperless voting machines... Result: lowest voter turnout in the world.
People who think they are going to vote in the upcoming election would do well to verify that they are still eligible.