Amid this crisis, Air Force One banked out of a crystalline blue sky and landed in what boosters have long described as “America’s desert oasis.” Having already exercised for nearly an hour in the gym of the InterContinental Hotel in San Francisco, the president — wearing a striped shirt with sleeves rolled up, light trousers and brown shoes. He was then driven through blocked streets to Sunnylands, the former Annenberg estate where political leaders and celebrities have come to rest and meet for decades.