In this photo by Sakchai Lalit, Thais hold portraits of Thailand's King Bhumibol Adulyadej outside Siriraj Hospital in Bangkok, where the ailing 88-year-old monarch has been treated for years. Several people had gathered at the hospital to pray and burn incense for the king's well-being. Bhumibol is the world's longest-reigning monarch and has been a key unifying figure in the Southeast Asian country. Thais are concerned about the eventual succession as he has been king since 1946 and the crown prince has not earned the same respect as his father. The king's health was described as unstable after he underwent procedures over the weekend to purify his blood and change a tube that drains excess cerebrospinal fluid.