Saruman for or against Sauron?

[davem]

I think there's also Saruman's envy of Sauron to take into account. Its clear that Saruman saw Sauron as some kind of 'ideal' role-model:

A strong place and wonderful was Isengard, and long it had been beautiful; and there great lords had dwelt, the wardens of Gondor upon the West, and wise men that watched the stars. But Saruman had slowly shaped it to his shifting purposes, and made it better, as he thought, being deceived--for all those arts and subtle devices, for which he forsook his former wisdom, and which fondly he imagined were his own, came but from Mordor; so that what he made was naught, only a little copy, a child's model or a slave's flattery, of that vast fortress, armoury, prison, furnace of great power, Barad-dur, the Dark Tower, which suffered no rival, and laughed at flattery, biding its time, secure in its pride and its immeasurable strength.(The Road to Isengard)

It seems that he wasn't so much competing with Sauron as wanting to become him. Whether Sauron was responsible for putting this desire into his mind, or whether it merely reflected some deep-rooted desire in his own psyche, I don't think we'll ever know for certain.