In Broward County, Florida, you had machines that started counting backwards (or did they wrap around in a fixed-size buffer?) after reaching certain numbers of votes. At least supposedly. Let's assume it is reasonable for these machines to have a number-of-votes limit. They should put up a warning message and fail to register votes, once the limit is reached. So failure to do this is a bug.
Now suppose you are management of the company that makes such a machine, and that you wish to help Leader Bush. You receive bug reports, and you decide which bugs get priority, or whether voting machine bugs get higher priority than other business activities. You can decide to give a bug low priority, and the sell those machines where they are likely to help Bush.
Voting machines should generate a hard copy record, and their hardware designs should be part of the public record, and the software in them should be "free" in the GNU sense. Making the software "free" would have similar benefits to those enjoyed by GNU Privacy Guard; the source code is free for anyone to review and to compile for themselves, mistakes or malicious code can be fixed by anyone hired to do it, and other benefits that I'll leave as an exercise for the reader.