I'm glad that you said "almost" I've never voted for a democrat in my life. I was convicted a little more than two years ago of carrying a gun. I didn't brandish it or threaten anybody with it. I simply had it.
In Illinois that's a felony. Fortunately for me Illinois still lets me vote.
If you're in jail, you lose privileges. One of those should be voting privileges.
There is a reason for this. With thousands of people of voting age in jails, those numbers could swing close elections, and having politicians pander to prisoner special interests for their votes threatens the integrity of the public offices.
It prevents the formation of a prisoner voting bloc, and you know that would happen.