cosign

verb

1. To sign a document jointly with another person, sometimes as an endorsement.
2. (informal, transitive)To agree with or endorse.

   “[Ilhan] Omar was left twisting in the wind earlier this year after facing spurious charges of antisemitism, a display of Democratic cowardice co-signed by Chelsea Clinton, Chuck Schumer, and most every other Democrat with a congressional leadership position.”

noun

1. The promotion of one musical artist (usually less successful) by another.

   “Also, you can't base your entire career on cosigns and big features. At some point, your music has to stand on its own.”

   “Big pump, don't stunt when it's showtime / Kinda funny how I didn't need a cosign”