What’s the cause of $4 for a gallon of gasoline? To listen to Democrats in Congress and on the campaign trail -- and also some Republicans -- the answer is “price gouging,” “speculation,” “oil companies” or “the failed policies of George Bush and Dick Cheney.”

Everything is getting blamed except the well-documented obvious: the law of supply and demand.

The history of U.S. energy policy is that Democrats have refused to increase supply and Republicans have refused to curtail demand. They are both to blame for $4 gasoline -- and they'd better get together to keep Americans from paying $200 a barrel to foreign oil producers.

Here’s what the federal Energy Information Administration says: “A variety of factors have caused oil prices to increase, including strong demand growth in non-OECD Asia and the Middle East, no growth in production since 2005 from the members of the Organization of Petroleum Exporting Countries, rising costs for oil exploration and development, across-the-board increases in commodity prices, and a weaker U.S. dollar.”

Simple translation: China and India are buying lots more oil, increasing overall demand, and OPEC is not producing more supply. Under such circumstances -- duh! -- prices rise.

Additionally, the United States, with its interest rates too low and chronically consuming more than it produces, has seen its currency lose value, so that every barrel of oil (and bushel of wheat) costs more.