Some on FR would argue, but I believe the POTUS could, if he wanted to, cut energy prices in half in a very short time. This could be achieved by announcing a federal policy to immediately begin to increase the supply and availability of petroleum, natural gas, coal, and electricity.
Increasing the supply of petroleum is easy. Green light Keystone and drill, drill, drill. Just the announcement of these steps will decrease the price. Why the repubs aren't using this as a campaign issue is beyond me.