Botswana's former president Ian Khama has vowed to vigorously campaign to dethrone his handpicked successor Mokgweetsi Masisi, now a bitter rival whom he accuses of being a threat to democracy, in next year's elections. With elections due next year Khama is preparing to return home to bolster the opposition into a coalition to remove Masisi through the ballot box. "I have to fix the mistake I made in appointing Masisi to be my successor," Khama tells AFP in Johannesburg, adding he plans to "join with other parties to ensure that he (Masisi) and his party lose the elections". IMAGES AND SOUNDBITES