Cut off their state issued credit cards, repossess their state issued vehicles for starters. Dock their pay for every single day they miss work. (What they do is work, isn’t it???) Cancel their ability to declare they live in Wisconsin and are no longer elible as a citizen to occupy office.
Reading through the state tax sites it looks like you need a full 1-year period to become a resident for tax purposes if moving from one of those states to another. You may also owe taxes as a part-year resident if you MOVED from one to the other permanently.
Presuming the Democrats didn't intend to become permanent residents of Illinois, it's going to be doggone difficult to tag them with Illinois residency. On the other hand, they all have OTHER INCOME. Could be they earned some of it doing work in a different state. Since they have temporarily relocated to Illinois it is possible they owe taxes on income earned in Illinois at some time in the prior year.
Some Illinois resident might well COMPLAIN ~ so hop to it!