backbencher

noun
1
(in the House of Commons in the UK and in certain other parliaments) a member who sits in the rows of seats at the back, and who does not have an important position in the government or the Opposition
نماینده مجلس غیرفعال, پشت‌ نشین, نماینده پشت‌نشین, عضو غیرارشد پارلمان
compare frontbencher