The two moves provide the clearest indication to date that Mbeki has decided to fire Zuma — and wants to sell his decision to his allies before announcing it to the nation.

By using Parliament to announce his decision on Zuma’s political future, Mbeki is also demonstrating to his allies that he is firmly in control of his cabinet and the state. He also has the option of a cabinet reshuffle.

Presidential spokesman Bheki Khumalo said Mbeki would “deal with issues arising from the judgment of Judge Hilary Squires” in Schabir Shaik’s corruption and fraud trial two weeks ago, in his address to Parliament today.

“It’s very rare that this happens,” Khumalo said, referring to Mbeki’s request for a joint sitting of Parliament.

The request came after Mbeki met top aides at the ANC’s head office yesterday.

Today’s joint sitting will be preceded by a meeting of the ANC national working committee. Sources said the meeting would include alliance leaders and strong Zuma backers Zwelinzima Vavi of the Congress of South African Trade Unions (Cosatu) and South African Communist Party secretary general Blade Nzimande.

In what is shaping up to be D-day for the embattled deputy president, the top management of the National Prosecuting Authority (NPA) is today weighing possible charges against him.

It is understood that legal experts will recommend that NPA head Vusi Pikoli charge Zuma.

A source close to the four-year long Scorpions investigation into Zuma said the authority would be studying evidence not introduced in Shaik’s trial.

Mbeki is expected to try and whip Zuma’s supporters into line at this morning’s ANC meeting by arguing that Zuma perjured himself by lying to Parliament about supposed loans he received from Shaik, his financial adviser, who was sentenced to an effective 15 years in jail for corruption and fraud last week.

Mbeki is expected to argue that Zuma lied to Parliament’s ethics committee by submitting a loan agreement that was found to be false by Squires.

The president is also expected to refer to Squires’ verdict that Zuma had a “generally corrupt” relationship with Shaik.

Today’s meeting with the alliance top brass is expected to be a heated affair, with Zuma supporters determined not to offer Mbeki the political cover he needs to move against his deputy.

Zuma’s backers are expected to ask Mbeki to explain his backing for former NPA head Bulelani Ngcuka’s 2003 statement that while he had “prima facie” evidence of corruption against Zuma, he would not charge him.

A senior alliance leader said yesterday: “This meeting will show if Mbeki is able to put the unity of the movement above his own narrow political interests.”

The Zuma fallout has tested unity in the ANC and its alliance like no other issue in the past 10 years. But yesterday, ANC spokesman Smuts Ngonyama tried to downplay the deep-seated divisions.

In a statement that might actually fuel division, Ngonyama accused alliance leaders of “spreading falsehoods” about the ANC.

He said media reports of divisions in the party were “fuelled by a handful of voices within the ANC and its alliance partners who willingly propagate such falsehoods in pursuit of individual agendas”.

Meanwhile, Cosatu president Willie Madisha told a meeting of Cosatu shopstewards yesterday that a “right-wing clique” inside the ANC was determined to break the alliance.

Zuma supporters are confident he will survive the onslaught inside the ANC.