Nineteen candidates have registered in Comoros to challenge outgoing President Azali Assoumani at the polls on March 24, officials said on Thursday.Only five of the 20 participants in the race are supported by parties in the Indian Ocean archipelago, where an arrangement to rotate power among the three islands helped quell years of discontent and coups in the late 1990s.The other 15 candidates are standing independently, according to the list compiled by the independent national electoral commission (CENI).The opposition is in disarray after dozens of arrests. A security court has handed down a string of jail terms to political figures who opposed a referendum allowing Azali to extend his term in office.Azali, who was voted into office in 2016, is tipped to win the election, defeating former vice-president Mohamed Ali Soilih as he did in 2016, and beating one-time armed forces chief of staff Colonel Soilihi Mohamed.The election will take place under the provisions of the constitution modified at Azali's initiative in the contested referendum held in July 2018.If a second round of voting is needed for the lack of an outright winner, it will be held on April 21.The constitutional reform enables the president to hold two five-year mandates instead of one. If Azali wins, he will be considered as starting a first term, which would allow him to vie for a second in 2024.The new constitution has retained the rotation of presidential power among Grande Comore, Anjouan and small Moheli, but the time period has been extended from five to 10 years.Azali's island, Grand Comore, currently holds the privilege. The opposition has denounced the threat to the fragile balance of powers that made it possible in the first years of the century to put an end to violent upheaval and separatist activity.Azali himself first seized power in a coup against an acting head of state in 1999 and was returned to office until 2006 in a multi-party vote. That year, power was transferred peacefully for the first time since independence from France in 1975.Today, Azali's critics consider that he has taken an authoritarian turn, with the possibility of staying in power until 2029. Dozens of opposition activists have been arrested in the past six months.The Supreme Court, whose judges were all named by Azali, has 10 days to examine the candidatures and accept or reject them.Elections for the governors of the three islands will take place at the same time as the presidential poll.Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and Facebook.