What is the origin of the idiom "throw someone under the bus" and when to use it?

The origin of the idiom "throw someone under the bus" is not definitively known, but it likely stems from the literal idea of someone being pushed or thrown beneath a bus, resulting in harm or betrayal. This phrase is used when someone is willing to sacrifice or betray another person to protect themselves or achieve their own goals. It often implies a lack of loyalty or a willingness to harm someone else for personal gain. This can happen in various contexts, including the workplace, relationships, or politics.