The Saudi Arabian monarchy has privately sought advice on what is likely to happen in the November US presidential elections and is shaping its policy towards Washington accordingly.   The US consulting firm they hired has provided them with a confidential assessment stating that the likely Democratic candidate Barack Obama will lose to Republican John McCain because he will be unable to overcome the concerns of some voters about his race, pretty much what Hillary Clinton has been predicting.  The Saudis have decided that they will send careful signals to president-to-be McCain that they support him and his candidacy. They have become disenchanted in their dealings with current President George W. Bush because they consider him to be fatally weakened by his lame duck status and the war in Iraq as well as insufficiently serious and an intellectual lightweight.  For that reason, last week they refused to increase petroleum production at his request and will wait for a McCain victory so that they can do a favor for the incoming president instead.