You need something like the British arrangement in India--dyarchy. There were certain subjects reserved to the center, like military, and certain subjects reserved to the regions, like economic growth. And it worked pretty well.
這和「日本模式」差不多：自民黨雖然也是一黨獨大，執政四十年，但只要還有其他政黨存在，它就不得不收斂一點、更努力一點，「有競爭才有進步」是絕對不會錯的。