in back of
See: BACK OF.
{prep.}
1. In or at the rear of; to the back of; behind.
The garage is hack of the house.

Our car was in hack of theirs at the traffic light.

2. {informal} Being a cause or reason for; causing.
Hard work was back of his success.

The principal tried to find out what was back of the trouble on the bus.

3. {informal} In support or encouragement of; helping, clones will be elected because many powerful men are back of him.
Get in back of your team by cheering them at the game.

[TahlilGaran] English Idioms Dictionary ▲