Well, if it were limited to just people moving an re-registering, that's one thing.GregD wrote:
I expect it is very common for people to move without "unregistering" and end up being registered in two places. Not much of a "gotcha" at all. More of an issue if someone actually voted in multiple places; that would be a pretty deliberate and illegal act.
We will never know the extent of the problem without an investigation, and people who move are just a part of the equation. I suspect that double voting is comparatively significant among college students who become politically active once they start college voting in both the State they call home and the one in which they are attending college---that's certainly plausible. To the extent to which this demographic skews Democrat, I can see why Democrats might not want to delve too deeply there. The other demographic is affluent Baby Boomers with retirement homes, beach houses, summer cabins and the like, as well as the very rich who have homes in multiple states. Politically active people in that demographic might abuse thier priveleges as well. Then there are the people who are dead who can still vote in states that don't require an ID to vote, unless the vote absentee.
There's a new study out that says at least 800,000 illegal aliens voted in the last election.
So, in a nation of 330 million people, we might expect to add maybe tens of thousands of college students, politically active retirees, affluent baby boomers, and dead people that could bring the total up to nearly a million.
Of course, that means Donald Trump was off by a million and a half, so you'd have that to hang on to.