be at the bottom of

US /bi æt ðə ˈbɑtəm əv/
UK /bi æt ðə ˈbɑtəm əv/
"be at the bottom of" picture
1.

estar na raiz de, ser a causa de

to be the real cause of something, especially something bad

:
I suspect he's at the bottom of this whole mess.
Suspeito que ele esteja na raiz de toda essa confusão.
We need to find out who is at the bottom of these rumors.
Precisamos descobrir quem está na raiz de esses rumores.