AFSCME is the largest union of state government employees, representing 100,000 workers, from janitors to prison guards.
Its endorsement of Dillard comes as another candidate says he got into the race to reduce the power of such unions.
Private equity investor Bruce Rauner says because government unions give campaign contributions to the very politicians with whom they negotiate, the entire system is "corrupt" and "immoral."
Which is why AFSCME, along with the two big teachers' unions, have endorsed Dillard.State Rep. Jil Tracy is Dillard's running mate.
"Many of our state workers are Republicans. And to demonize a whole category of people that work very hard in our state government, and to demonize teachers, is incredible to me."
AFSCME says its going to encouraging its members to vote for Dillard ... and against Rauner.But with less than two weeks until the election, Rauner has already spent millions of dollars on television advertising -- while Dillard hasn't been able to afford any.