CUT THE GROUND FROM UNDER
cut the ground from under: translation
{v. phr.} {informal} To make (someone) fail; upset the plans of; spoil the argument for (a person) in advance. * /Paul wanted to he captain but we cut the ground from under him by saying that Henry was the best player on the team./ * /Several workers applied for the retiring foreman's job, but the owner cut the ground from under them by hiring a foreman from another company./