hold the reins

Etymology

A metaphor, based on the usual method of controlling a horse or a team of horses.

Verb

hold the reins

1. (idiomatic) To be in charge, to be in control, as of a business, political organization, or other group.
   • 1918, "Washington Believes Foch Will Still Accept Envoys' Signatures," Toronto World, Nov. 11, p. 1:

     These terms . . . will place the future behavior of Germany at the dictation of the associated powers regardless of what form of provisional government may hold the reins at Berlin.

   • 1996, Michael Serrill, "Mexico's Black Mood," Time, 7 Oct.:

     The convention also delivered a slap to the technocrats who have held the reins of government for more than a decade.

   • 2003, Cathy Lynn Grossman, "Baptist missionaries at odds with church," USA Today, 20 April:

     While conservatives hold the reins at the SBC, moderates have retained control of the Baptist General Convention of Texas.