Harare – Zimbabwean First Lady Grace Mugabe has reportedly declared that under fire Vice President Emmerson Mnangagwa should be gone from both the government and Zanu-PF, before the ruling party's extraordinary congress in December.Grace said this as she addressed thousands of indigenous church followers during what was termed a "Super Sunday Rally" at a stadium in Harare on Sunday.According to NewsDay, the "angry" First Lady said: "Trouble causers in the party must go before the next congress. He (Mnangagwa) must be dropped before we meet at congress in order for us to have unity in the party."Mnangagwa, who had been touted as a possible successor to President Robert Mugabe, 93, has recently fallen out with the first family.On Saturday Mugabe threatened to fire Mnangagwa, accusing him of fanning factionalism to garner support ahead of the special congress.Coup Amid party divisions over who should become leader - an event only likely to occur when the incumbent dies – Grace 52, said the party will soon change its constitution to allow a woman to be vice president, reports indicated. The move would likely see her replace Mnangagwa and pave the way for her to succeed her husband, who is Africa's oldest president and has ruled the former British colony for 37 years.Mnangagwa was appointed vice-president in 2014, taking over from Joice Mujuru - who was axed after Grace launched a campaign accusing her of plotting to topple the president.Mugabe's wife on Sunday also accused Mnangagwa of a dark past of clandestine plots, including planning to stage a coup around the time of Zimbabwe's independence in 1980."In 1980 this person called Mnangagwa wanted to stage a coup. He wanted to wrestle power from the president. He was conspiring with whites. That man is a ravisher," said Grace.Despite his advanced age and concerns over his health, Mugabe has refused to name a successor.He has been endorsed as his party's candidate for next year's election.