Happened to Bush Jr. during the 2008 elections. So don't act all surprised when the same happens to Obama.
You can't nationalize them. Almost all oil companies are
international. How do you think other countries are going to react when you start taking away pieces of their companies??
In an international market, the only way to get prices down is to increase the supply (you have no control over demand, because most of that demand comes from other countries you can't control without dropping bombs on them). Yes, any additional oil we drill domestically will go to the international market--so the only way to reduce gasoline prices in the U.S. is to increase the supply of oil
in the international market.
Side note: gas prices aren't only going up in the U.S., they're setting records in Europe as well.