Our Daily Bleg: If You Don’t Bargain With Chips, Why Say It?

Here’s the most recent guest bleg from Fred Shapiro, editor of the Yale Book of Quotations. His past blegs can be found here. Send us your own bleg requests here.

For years I have been posing a question about the term “bargaining chip” that no one has yet answered.

This is widely assumed to be a poker metaphor, but I do not know of chips being used for bargaining or trading in poker or any other game. What exactly is the metaphor?