Demand is the most important driver of the oil price. As said, demand declined sharply when the oil reached the range of $140. Even speculation can not afford the decline of the demand, so the oil price came off from that level and I don't expect it to retouch that level any time soon before the election is done.
However, the supply is not enough for sure. They have trouble to get oil in middle east, according to my friend who is an engineer over there. He said it is really hard to dig out the oil these days.