By dragging him into scandals, including one about an alleged love affair with a personal assistant who works at the ANC headquarters, Luthuli House, Motlanthe’s enemies apparently want to make him less of a threat to the ambitions of Jacob Zuma, the ANC president.
A plan is also being hatched to clip Motlanthe’s wings by not allowing him to make the traditional state of the nation address in 2009.
Instead, he will be restricted to giving a "report-back" to the nation, according to insiders in Luthuli House.
This was corroborated by two government officials who refused to be quoted because the matter was not yet official.
Another ANC staffer sympathetic to Zuma said the reason for this would be a way of avoiding "this false notion that the nation warms up to [Motlanthe]".
But authoritative sources say Motlanthe is not interested in returning to Cabinet service after 2009’s general election, when Zuma is expected to become president, because this would mean a demotion.
In terms of official protocol, as the former president, Motlanthe would still assume the same presidential status even if he were to be appointed deputy president or a minister, creating a hierarchical nightmare. It is understood Motlanthe would want to avoid such "confusion".
Nzimande, according to several insiders in the alliance, is part of a clique that believes that Motlanthe has ambitions to stay on if the ANC wins 2009’s elections.
Malesela Maleka, the SACP spokesperson, denied any bad blood between the two leaders, saying the allegations were part of a campaign to "smear" Nzimande.
"It’s a lie. This is [the work of] people who want to sow divisions in the movement and the leadership of the alliance. We know this is the beginning of a series of allegations as part of a plot to isolate Blade from the movement," he said.
In the latest round of backstabbing, Motlanthe’s love life is to be targeted. Nzimande is leading a lobby to isolate the ANC deputy president, a Luthuli House staffer said. He refused to be named because "these are not policy or organisational issues".
Motlanthe, a married father of three, has kept his family life out of the public eye, but an ANC leader said Motlanthe’s caginess about his personal life "is a problem" and "this cannot be blamed on a conspiratorial plot or Zuma".
"Kgalema’s marital life is [not that rosy]. He must take responsibility for it; no one is to blame for it," he said.
Nzimande is said to have briefed union leaders about "Motlanthe’s ambitious plan" to frustrate Zuma.
The SACP leader apparently cited Motlanthe’s reluctance to withdraw the Cabinet’s intention to appeal against Judge Chris Nicholson’s ruling as an indication that the president "wanted Zuma to fry".
This was confirmed by three independent sources who are not in the ANC. Apparently, Nzimande also criticised Motlanthe for not having attacked the breakaway faction of the ANC, now campaigning as the Congress of the People (Cope).
His enemies see this as an indication that the president was going to join the breakaway party. To bolster his argument, Nzimande cited Motlanthe’s Cabinet decision to sell Telkom’s Vodacom shares to Vodaphone – in a deal that involved a company linked to one of COPE’s leaders and Smuts Ngonyama, the former ANC spokesperson – as evidence that the president wants to finance the breakaway party.
Maleka said the party had publicly raised concern over the deal.
Another charge is that Motlanthe has refused to appoint SACP-recommended ministers. Tensions have also been sparked by Motlanthe’s appointment of finance minister Trevor Manuel and former minister Valli Moosa – both pro-Mbeki – to the deployment committee against the wishes of ANC hardliners.
There is also unhappiness about the cordial relations between Motlanthe and Thabo Mbeki, the former president. Mbeki’s influence is also offered as an explanation for Motlanthe’s soft approach towards Zimbabwean President Robert Mugabe.
Motlanthe appeared with Mbeki at the Reconciliation Day celebration while Zuma and COPE’s leaders were facing off at two separate rallies in Bloemfontein.
Presidential spokesperson Thabo Masebe refused to comment, saying that "these are party matters".
But Carl Niehaus, the ANC spokesperson, said: "There are absolutely no tensions. We are not aware of anything like that."