hold sway (over someone)

To have or exert great control or influence (over someone). My father retired from politics years ago, but he still holds sway in the town to this day. It is suspected that the president's wife holds a lot of sway over the administration's policy. Summer seems like a different person these days. I worry that her boyfriend holds too much sway over her.

hold ˈsway (over somebody/something)

(literary) (of a person, a movement, an idea, etc.) have power, control or great influence over somebody/something: Rebel forces hold sway over much of the island. ♢ These ideas held sway for most of the century.

hold sway

To have a controlling influence; dominate.