text: (CNN)Sri Lanka's current president Mahinda Rajapaksa has conceded defeat to rival Maithripala Sirisena in the country's presidential election, bringing an end to a decade of leadership increasingly criticized as corrupt and nepotistic. 
  
  Rajapaksa acknowledged the defeat on his official Twitter account Friday, writing: "I value and respect our democratic process and the people's verdict, and look forward to the peaceful transition of power." 
  
  Sirisena would be sworn in at 6 p.m. local time in Colombo's Independence Square, Dhanushka Ramanayake, the head of his media unit, said. 
  
  The defeat of the once untouchable president, the longest-serving political leader in the region, was the result of a failed electoral gamble. 
  
  In November, the 69-year-old called elections two years earlier than required, only to be shocked by the defection of many key political allies, including the man who would unseat him. 
  
  The defections apparently wrong-footed Rajapaksa, and the opposition had the better of the campaign, say analysts. 
  
  "He didn't expect the candidate to be Sirisena," said Paikiasothy Saravanamuttu, executive director of Sri Lanka's Center for Policy Alternatives. 
  
  "I think he probably underestimated the disaffection in the country and the desire for change." 
  
  Unexpected departure 
  
  Sirisena, 63, served as general-secretary of Rajapaksa's Sri Lanka Freedom Party and health minister in his cabinet, before switching allegiance to a broad opposition alliance that proved to be the former president's most serious political challenge. 
  
  The unwieldy coalition includes the center-right United National Party, the hardline Sinhala Buddhist Jathika Hela Urumaya as well as parties representing the substantial Tamil and Muslim minorities. 