This idiom or expression has to do with:

Having a powerful punch.
Having a lot of power or influence.

Hey, your kid brother really packs a punch. I’m still dizzy!

This idiom or expression like phrase means:

Powerful people.
The government.
The people in charge.
People whose opinions matter.
Those who control public affairs.
Those who make the important decisions.

The powers that be are interested in this casino development. So, it will happen!