Addendum: The state law is all that matters; any political party would be subject to a change in the state law. Therefore, the Democrats would not have to “agree”.
I understood, but was just asking as a practical matter. Even here in Texas (open primary), I doubt you could get a bill to close the primary without some sort of agreement between the parties.
BTW, next year is the only shot for a change here in TX. Legislature doesn't meet in 2012 unless a special session is called.