non-starter
/nɒnˈstɑːtə(r)/noun
1- a person or animal that fails to take part in a race未能参加赛跑的人（或动物）。
1.1
- informal a person, plan, or idea that has no chance of succeeding or being effective〈非正式〉无望获胜的人; 无望实施的计划; 不切实际的想法。