stem the tide
Stop the course of a trend or tendency, as in It is not easy to stem the tide of public opinion. This idiom uses stem in the sense of “stop” or “restrain.” [Mid-1800s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.