throw in your lot with
throw in (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 throw in her lot with us. Don't worry, Mom—I really don't care about throwing in my lot with the cool kids at school.
throw in your lot withdecide to ally yourself closely with and share the fate of a person or group.
Both this and the previous idiom come from the process of deciding something by drawing or casting lots.
1992 Michael Medved Hollywood vs. America Yuppie physician Michael J. Fox decides to give up his dreams of glitz and glory in L.A. and to throw in his lot with the lovable locals.