Complex sentence: Upon Jiang's retirement in 2003-4, it is widely believed that he stuffed the cabinet with all his men, and is said to be making it difficult for Hu and Wen to carry out their own policies.
Split into simpler sentences: Upon Jiang's retirement in 2003-4, it is widely believed that he stuffed the cabinet with all his men. This is believed to be making it difficult for Hu and Wen to carry out their own policies.