political suicide
Refers to a politician or political group destroying their own career or standing through their actions or statements.
The scandal led to the minister's political suicide.
His radical remarks were political suicide.
自滅 means self-destruction or ruining oneself in general, while 政治的自滅 specifically refers to political self-destruction.
Compound of 政治的 (political) + 自滅 (self-destruction).