(CNN)There were wild celebrations in the Zimbabwean capital Harare when Robert Mugabe bowed to the inevitable and resigned as President on Tuesday. But as Zimbabweans feted his demise, it was unclear whether they would welcome the man in line to succeed him with such enthusiasm.
Emmerson Mnangagwa, the 'crocodile,' in line to be Zimbabwe's next leader
Until Mugabe fired him as vice president earlier this month, Emmerson Mnangagwa's entire political career had been hitched to Zimbabwe's 93-year-old former leader.
But Mnangagwa has been eying the presidency and maneuvering to dethrone Mugabe for some time. Sources told CNN that he was instrumental in the military's apparent coup that led to Mugabe's political demise.
Mnangagwa is expected to be sworn in as president by Thursday, according to Simon Khaya Moyo, the spokesman for Mugabe's ZANU-PF party.
It is not the first time that Mnangagwa has been in line to lead Zimbabwe.
A core member of Mugabe's ruling circle and a combat-hardened veteran of the struggle for liberation from white-minority rule, Mnangagwa was mooted as a potential presidential successor in leaked US diplomatic cables as far back as 2000.
Those cables, part of a huge cache leaked to whistleblowing website Wikileaks by US army soldier Chelsea Manning, paint a picture of a canny political operative, who has surfed the waves of Zimbabwean politics, navigating periods both in and outside of Mugabe's trusted inner circle.
They also hint at Mnangagwa's dark past. In late 2000, a cable written by Earl Irving, then a US diplomat in Harare, described Mnangagwa as "widely feared and despised throughout the country," warning he could be "an even more repressive leader" than Mugabe if he were to succeed him.
Fear of Mnangagwa stems from his position as Mugabe's enforcer and head of the Central Intelligence Organization (CIO), or secret police, and his alleged role in the 1983-84 massacres of the Ndebele ethnic group in Matabeleland, a region in Zimbabwe's southwest that was a center of political opposition to Mugabe's regime.
The International Association of Genocide Scholars (IAGS), an international nonpartisan organization, estimate at least 20,000 civilians were killed by the CIO and the armed forces.
"Most of the dead were shot in public executions, often after being forced to dig their own graves in front of their family and fellow villagers," IAGS said in a 2011 report.
Kate Hoey, a British Labour MP who has campaigned for years to highlight oppression under the Mugabe regime, described Mnangagwa in a parliamentary debate last week as "probably the one person in Zimbabwe who inspires even greater terror than Mugabe."
Responding later in the debate, Boris Johnson, the British Foreign Secretary, called for elections to choose a new leader. "Nobody wants simply to see the transition from one unelected tyrant to the next," he told the House of Commons, hinting at years of allegations that Mugabe only won elections by rigging the votes.
"We want to see proper free and fair elections next year and that's what we will be working towards."
Nicknamed the "Crocodile" on account of his political longevity and survival skills, Mnangagwa has for years been thought to be biding his time, ready to takeover from Mugabe when the nonagenarian finally stepped aside, or died.
His impeccable revolutionary credentials, coupled with his strong support among key parts of Zimbabwe's elite -- specifically within the military and security services -- singled him out as an obvious, and non-controversial, successor.
But this was to dramatically change two weeks ago, when Mugabe sacked Mnangagwa, in a move to shore up the power of his wife and chosen successor, Grace Mugabe.
A statement from the country's information ministry accused Mnangagwa of "disloyalty, disrespect, deceitfulness and unreliability," sending him into hiding amid reports he was attempting to build a coalition to take on Grace Mugabe in the next election.
"One after the other, (Mugabe's) vice presidents and people around him were estranged by Grace Mugabe," said Geoff Hill, author of "What happens after Mugabe?".
"Nobody knows whether it was her, or whether he wanted a safe pair of hands. Either way it was a very unpopular move."
After senior army figures criticized Grace Mugabe's growing power earlier this month, they have succeed in removing her -- and her husband -- from the picture altogether.
"The army very quickly promised to restore the country to democracy, something Zimbabwe hasn't seen for a long time," said Hill. "They want to have a very inclusive government, possible even with (opposition leader) Morgan Tsvangirai coming in as vice president."
After Mugabe's resignation on Tuesday, it was not immediately clear how events would unfold. But one thing seems clear: After three decades waiting in the wings, Mnangagwa is in pole position to ascend to the country's top job.