backbench
noun [ C usually plural ] uk/ˌbækˈbentʃ/ us/ˌbækˈbentʃ/
（英国议会的）普通议员席，后座议员席
(the seats used by) members of the British Parliament who do not have official positions in the government or in an opposing political party
The prime minister expects strong support from the Labour backbenches. 首相希望得到工党后座议员的强有力支持。
a backbench revolt 后座议员的一次反抗
Compare: front bench