Political suicide is the concept that a politician

Politician

A politician, political leader, or political figure is an individual who is involved in influencing public policy and decision making...

 or political party

Political party

A political party is a political organization that typically seeks to influence government policy, usually by nominating their own candidates and trying to seat them in political office. Parties participate in electoral campaigns, educational outreach or protest actions...

 would lose widespread support and confidence from the voting public by proposing actions that are seen as unfavourable or that might threaten the status quo

Status quo

Statu quo, a commonly used form of the original Latin "statu quo" – literally "the state in which" – is a Latin term meaning the current or existing state of affairs. To maintain the status quo is to keep the things the way they presently are...

. A politician who committed political suicide might be forced to resign. A political party could stand to lose followers by deviating greatly from its core values and policies. Another term for such policies are "the third rail

Third rail (metaphor)

The phrase third rail is a metaphor in politics to denote an idea or topic that is so "charged" and "untouchable" that any politician or public official who dares to broach the subject would invariably suffer politically.-Denotation:...

".