bail
fall back
undercommit
welch
renegue on
go back on
renege
renege on
miss
miscarry
fainaigue
mismeet
go nowhere
forfeit
miss the mark
spoil the ship for a ha'p'orth of tar
underachieve
default
strike out looking
neglect
omit
promise the moon
drop the ball
mispledge
die on the vine
bite the big one
under-accommodate
scantle
leave someone out in the cold
bottle out
founder
go over like a lead balloon
push one's luck
retract
nonconform
wither on the vine
leave someone cold
repine
go down in flames
flake
write checks one can't cash
disobey
require improvement
hit the skids
missuit
not win for losing
languish
fall flat on one's face
self-handicap
whistle in the wind