fall asleep at the wheel

To fail to attend to one's responsibilities or duties; to be inattentive to that which is important or for which one is responsible. Johnson was supposed to make sure the paperwork went through before the deadline, but it looks like he fell asleep at the wheel. Our goalkeeper is such a nincompoop. We would have won that match if he hadn't fallen asleep at the wheel! How could you forgot to pick up the kids? Geez, you fell asleep at the wheel, right when I needed your help the most.