HARARE, ZIMBABWE — Zimbabwe’s vice-president was a rebel commander known as “Spill Blood” during the war against white rulers and, at the age of 25, became the youngest Cabinet minister after independence. Now she is a political pariah, accused of plotting the downfall of President Robert Mugabe with the help of nocturnal sorcery.

The rise and fall of Vice-President Joice Mujuru follows a pattern repeated over the years under 90-year-old Mugabe, a shrewd operator who has ousted rivals and cracked down on opponents during his long rule, dodging repeated predictions of his political demise. He has also sought to turn his tense ties with the West, a critic of his human rights record, into a rallying cry for nationalist support.

On Saturday, a ruling party congress is expected to announce new leadership that will reinforce Mugabe’s grip on power and reveal his possible successor. A front runner is Justice Minister Emmerson Mnangagwa, who suffered the same treatment as Mujuru a decade ago but is back in favour.

Recently, a beaming Mnangagwa was the guest of honour at a soccer match honouring Mugabe.

Mujuru, once favoured to succeed Mugabe, is unlikely to stay as vice-president following months of increasingly vitriolic attacks on her by Mugabe allies, according to political observers. This week, Mugabe himself criticized his old associate, saying Mujuru was told by a witch to get two river beetles, name them after herself and the president, and store them in a water jar.

“They were made to fight and if Mugabe’s beetle dies, then she will rule. I don’t know what would happen if the Mugabe beetle won. I think that’s what happened,” Mugabe said in the local Shona language to ruling ZANU-PF party leaders on Wednesday.

The dismantling of Mujuru’s political stature has been systematic.

Mugabe allies have elevated Mugabe’s wife Grace, a fierce critic of Mujuru who is expected to be appointed as head of the women’s league of the ruling party. They have cast doubt on Mujuru’s claim to have shot down an army helicopter during the independence war in what was then called Rhodesia.

The vice-president has been accused of corruption, a chronic problem in a struggling country whose economic chaos forced it to replace its currency with the U.S. dollar in 2009.

Mujuru, who has not attended the ruling party congress this week, has said she is loyal to the president and institutions of Zimbabwe.

“I regret that certain persons have elected to make false, unsubstantiated, malicious, defamatory and irresponsible statements about me,” she said in a statement last month.

In past months, talk of who will succeed Mugabe had increased in some party circles. But the current political reshuffling suggests that it remains a sensitive, if not taboo, subject. In power since 1980, Mugabe last year won elections that the opposition said were marred by fraud. He would be eligible for another term which, if he wins, would keep him in power until age 99.

Analysts describe the political purge as a classic tactic that Mugabe has used over the years against anyone who has challenged him.

Mujuru’s husband Solomon, a politically influential retired army general and businessman, died in a mysterious fire in 2011. One of her supporters said she was resilient and would re-emerge in politics because she has grassroots support.

“That woman is strong,” said Rugare Gumbo, who was recently ousted as ruling party spokesman. “She will be back.”