(figuratively, idiomatic) When the pressure is on; when the situation is critical or urgent; when the time has come for action, even if it is difficult.

(idiomatic) to perform an action before being forced to do so.

(idiomatic) To do something pointless or unnecessary; to try doing something already done.

simple past tense and past participle of push against an open door

Third-person singular simple present indicative form of push against an open door

So as to push.