I read a couple of years ago it was @ 250,000 for back support.
Here's more information from Tennessee, but his involves felons:
"Felons with unpaid child support can't vote"
http://www.knoxnews.com/kns/state/article/0,1406,KNS_348_5036789,00.html
Damn ! They now want you to register to read article.
Why the change all of the sudden ???
Just did a little Google research on it. Apparently the number is not known with any degree of certainty. The anti-child support website said that the actual number is a "secret" but it's around 25-50% of all men in county jails.
I suspect that it's no where near a million. Even 250,000 seems high, but that might at least be plausible. The article makes it sound like this is intended to keep GOPers from voting.
I suspect that the overwhelming number of deadbeat fathers are Democrats.