From WordNet (r) 3.0 (2006) :
drop by the wayside
v 1: give up in the face of defeat of lacking hope; admit
defeat; "In the second round, the challenger gave up" [syn:
drop out, give up, fall by the wayside, drop by the
wayside, throw in, throw in the towel, quit, chuck
up the sponge] [ant: enter, participate]