The blame for oil prices in the United States falls on everyone in the world.  What this means is that global demand for oil is the major cause of increase in oil prices over the years.

As you say, some people blame the President.  The idea behind that is that he and the Democrats resist drilling for oil in some places, like the Arctic National Wildlife Refuge (ANWR).  The idea is that if we could extract more oil, supply would go up and prices would go down.  Others blame the oil companies and refineries.  They say that these suppliers artificially keep supply low so that they can charge higher prices.  

There is some truth to both of these charges.  However, the more important cause of the higher oil prices is rising demand around the world.  As China becomes richer, for example, more Chinese people have cars and other possessions that require energy.  This increases the demand for oil worldwide.  As demand rises, oil prices will rise unless supply can increase along with the demand.