The state government would put forwards a local movement to secede from the US, and if it actually passed the federal government would butt in and go “you can’t secede, that’s completely illegal and unconstitutional” (it is), at which point the state would either go “oh well” and stand down or say “go suck eggs” and continue trying to secede, which the federal government would treat as rebellion or insurrection.
The state government would put forwards a local movement to secede from the US, and if it actually passed the federal government would butt in and go “you can’t secede, that’s completely illegal and unconstitutional” (it is), at which point the state would either go “oh well” and stand down or say “go suck eggs” and continue trying to secede, which the federal government would treat as rebellion or insurrection.
Even if the federal government says “okay”. They may actually turn around and pretend it never happened… or they can start a war with them.