The term "lame duck" in politics originated in the 18th century and refers to a politician whose term in office is ending, especially when their successor has already been elected. This person is seen as having limited power or influence, much like a lame duck cannot fly.
The phrase likely evolved from the world of duck hunting, where a duck with a broken wing was unable to fly and therefore easy prey. Similarly, a politician whose term is about to end is seen as vulnerable and ineffective.
While the phrase "lame duck" might conjure up images of horses with injuries, its origin lies in the political realm, where it signifies a diminished power and influence at the end of a term.