How about a very public proclamation by some government figures, reminding everyone of the jail time and fines associated with voter fraud, and that the state, local and federal agencies will be pursuing this vigorously. Scare the hell out of anyone who is planning to do this, and then follow up on it (unlike the non-follow up that took place after 2000, when everyone on Free Republic predicted this was going to happen 4 years hence).
Then, wait for the reaction from the Dems about how the evil Republicans are trying to "intimidate voters and suppress minority voting, denying them their civil rights".
They would have, of course, the full and vocal support of the Mainstream Media Choir. We can all readily imagine the sulphurous pronouncements of the New York Times editorial board.
So, because they're afraid of being called names by the MSM, the Pubbies will do nothing. Once again...