This effort should not be allowed to fail. And that means the time may soon come - I believe we don't have much time left - when it will be necessary to move from mediation to arbitration. Two possible forums for arbitration are the U.N. Security Council and the so- called quartet of Middle East peacemakers - the United States, Russia, the European Union and the United Nations. The United States is the foremost power in both. The key would be that the terms of the final status settlement be defined by an arbiter if the two sides fail to agree. Reaching a settlement in this manner may carry risks, but the cost of continued failure is much greater.