cast one's 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
Farlex Dictionary of Idioms.

cast one's lot with

Also, cast or throw in one's lot with . Join or side with, no matter what the outcome, as in Bill cast his lot with the new company. [First half of 1500s]
See also: cast, lot
The American Heritage® Dictionary of Idioms by Christine Ammer.
See also:
  • cast (one's) lot with (someone or something)
  • cast lot with
  • throw in (one's) lot with (someone or something)
  • throw in your lot with
  • throw in your lot with somebody
  • throw in your lot with someone
  • to a person
  • blow (something) wide open
  • blow something wide open
  • blow wide open
References in periodicals archive
But it would be a mistake to cast one's lot with the minority of readers willing to pay for online news, while ignoring the major transformations happening around us.
One cannot in one motion cast one's lot with the unprotected.