Yesterday, in what was presented as an innocuous 63rd birthday greeting to Motllanthe, the league said he would, in a few months, drive the ANC mandate.

"Undoubtedly, Comrade Kgalema Motlanthe is the future of the ANC and South Africa," the league said.

This endorsement - together with other recent examples - is in blatant defiance of the ANC's prohibition on open discussion of leadership issues before October, two months before the party's elective congress in Mangaung.

In its birthday message, the league said: "As we wish him health and happiness for years to come, we are confident that the very values of principle, integrity and humility that define him will, when the time comes in the next few months, guide him in the execution of the mandate that the overwhelming majority of ANC members will bestow upon him to drive the charge for the realisation of the aspirations of the people as articulated in the Freedom Charter."

For months, the league - including its expelled president, Julius Malema - has been silently campaigning for Motlanthe to replace Zuma at Mangaung.

The defiance is not limited to the youth league. Last week, ANC members in Limpopo openly showed their preference for Motlanthe when they displayedbumper stickers bearing his name on their cars.

During the ANC centenary flame rally at Nkowankowa, near Tzaneen, Limpopo, party members displayed stickers proclaiming: "Kgalema for president come Mangaung."

Last week, during a lecture on former president Nelson Mandela by Zuma, youth league members aligned to Malema heckled and disrupted the proceedings, resulting in some of them being arrested.

Youth Day celebrations last month turned violent when league members sang pro-Motlanthe songs while calling for Zuma's removal as ANC president.

To his credit, Motlanthe has taken the league to task when they use his name to campaign for change in the ANC.

He rebuked the youth league when some of its members revealed T-shirts bearing his image.

He has refused to openly declare his presidential ambitions.

However, the league said it was for this reason that it held him in high regard.

"He never misses an opportunity to remind us that it is our obligation, as young people, to constantly question and fearlessly challenge the status quo for, indeed, it is our future that the ANC today has a responsibility of crafting.

"He is also not one to sacrifice principle at the altar of expediency and, as the ANC Youth League, we have had first-hand experience of his humility and leadership."

The league said Motlanthe did not turn "a blind eye to instances where the traditions, practices and guidelines of the organisation are violated, whether such violation is in his favour or not".

The league boycottedZuma's 70th birthday party.

Zuma is the only president not to receive glowing birthday wishes from the league. Nelson Mandela and Thabo Mbeki were showered with praises.