I am in total agreement with
Gandalf the White.
Sauron had invested much of his power in
the One Ring and, as such, could not be taken off the plane of
Middle Earth until
the Ring was destroyed. No other
Maia had attempted to create such a
Ring of Power and imbue it with so much of themselves.
It is ironic though that
Tolkien himself made the following statement in the Foreward to The Fellowhip of the Ring while talking about allegory in his work, "The real war does not resemble the legendary war in its process or its conclusion. If it had inspired or directed the development of the legend, then certainly the Ring would have been seized and used against Sauron; he would not have been destroyed but occupied.
Saruman, failing to get possesion of the Ring, would in the confusion and treacheries of the time have found in
Mordor the missing links in his own researches into Ring-lore, and before long would have made a Great Ring of his own with which to challenge the self-styled Ruler of Middle-earth. In that conflict both sides would have held
hobbits in hatred and contempt: they would not have survived even as slaves."
He hints here that maybe Saruman(and if Saruman, why not Gandalf?) could, with the right information from archives in the
Barad-dur, make his own
Ruling Ring. Who woulda' thunk???