Support or have good relations with two opposing sides. For example, He had a foot in both camps, making donations to candidates in both parties. In this expression camp alludes to encampments of enemy troops in a battle. [First half of 1900s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.