Hold The Reins Meaning

(idiomatic) To be in charge, to be in control, as of a business, political organization, or other group.

Example: 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.