redress the balance
Readjust matters, restore equilibrium, as in If our party wins in a few big cities, it will redress the balance of urban and rural interests in the House. [Mid-1800s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.