The phrase "on hot seat" is an idiom that means someone is under intense pressure or scrutiny. There are many synonyms for this phrase that can be used interchangeably. These include being in the spotlight, being in the firing line, being in the line of fire, being under the microscope, being under the gun, being under scrutiny, being under pressure, and being under the microscope. Each of these synonyms can be used in different contexts, and they all convey the same sense of someone being under intense scrutiny or facing a difficult situation. It's important to choose the right synonym depending on the situation, but each of these options is a good alternative to "on hot seat".