chicken out

verb

1. To shy away from a daring task; to decline, refuse, or avoid something due to fear or uncertainty.

   “We almost convinced his dad to ride the roller coaster, but he chickened out when he saw how high it went.”

   “I dismiss Reporters Without Borders. Completely nonsensical. We invited them in for a select committee hearing, and in the true heritage of free speech, they chickened out.”