Trying to press the kind of unwanted fundamental political change on a ruling elite in similar to playing a game in which one's opponent can change the rules at any time s/he likes.
One是trying to press…on a ruling elite的主语。A ruling elite和one’s opponent是同义词。所以这句话应该是
想迫使统治精英接受他们不想发生的重大政治变革改变 ,就好比玩一个对手可以在任意时刻改变规则的游戏。