Complex sentence: Ozawa's autocratic leadership style alienated many of his former allies, and even Tsutomu Hata, disillusioned after his leadership battle with Ozawa, seceded to form the Sun Party in 1996.
Split into simpler sentences: Ozawa's autocratic leadership style had alienated many of his former allies. Even Tsutomu Hata, disillusioned after his leadership battle with Ozawa, seceded to form the Sun Party in 1996.