cast lot with

cast (one's) lot with (someone or something)

To join and steadfastly support another person or group. As soon as news of the CEO's scandal becomes public, I doubt that big investor will want to cast her lot with us. Don't worry, Mom—I really don't care about casting my lot with the cool kids at school.
See also: cast, lot

cast (one's) lot with

To join or side with for better or worse.
See also: cast, lot