Brazzaville - A former Congolese army chief and presidential advisor announced on Monday he plans to run in the March 20 election and challenge President Denis Sassou Nguesso, who has been in power in Congo-Brazzaville for more than 30 years."I will be a candidate... I felt called to by the people and I decided to cross the Rubicon," General Jean-Marie Michel Mokoko told AFP by phone from Bangui."I know the country well, its challenges and its history," the ex-officer in his sixties, who wants "to propose projects and a lot of reforms", said without elaborating.Congo's military chief from 1987 to 1993, Mokoko is currently special representative of the African Union Commission in Central African Republic.Mokoko is a longtime ally of Sassou Nguesso, but on February 3 he announced his resignation as the president's advisor on peace and security, a post he had held since 2005.He becomes the eighth candidate vying to replace the central African country's leader and his nearly 32 years in power. Sassou Nguesso is seeking re-election after winning a referendum that eliminated the constitution's two-term limit. He led Congo under one party rule from 1979 to 1992, then returned to power after a civil war in 1997 and won multi-party polls in 2002 and 2009.