stem the tide, to

To stop something from continuing or worsening. Once the people turn on you, you'll have a hard time stemming the tide of rebellion.

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]

COMMON If you stem the tide or stem the flow of something bad which is happening to a large degree, you start to control and stop it. The authorities seem powerless to stem the rising tide of violence. The cut in interest rates has done nothing to stem the flow of job losses.

To stop the course of a trend, opinion, or the like. The verb to stem, meaning to stop or restrain, comes from the Old Norse word stemma, meaning “to dam.” It would take an enormous dam to stop ocean tides, but the tide of public opinion, for example, can be checked or diverted. Thus Fred A. Paley wrote (The Tragedies of Aeschylus, 1855), “Aristophanes evidently saw the tide . . . and he vainly tried to stem it by the barrier of his ridicule.”