When Americans succeeded in Arab-Israeli diplomacy, it was because they were respected, admired, even feared. U.S. power and influence were taken seriously. Today, much of the magic is gone: We are overextended, diminished, bogged down. Again Summers: Can the world's biggest borrower continue to be the world's greatest power? Our friends worry about our reliability; our adversaries, including Hamas, Hezbollah, and Iran, believe they can outwait and outmaneuver us. Nor does there appear much cost or consequence to saying no to the superpower. After Obama and Mitchell's fruitless first year, I worry that the mediator's mystique of a Kissinger or a Baker, or the willfulness and driving force of a Carter, won't return easily.