The powerful Congress of South African Trade Unions (COSATU) has endorsed former Vice President Jacob Zuma to lead the ruling African National Congress (ANC).

COSATU General Secretary Zwelinzima Vavi says the group approved the endorsement Thursday.  The trade group is a junior member of the ruling coalition.

The party leader is generally seen to be the favorite in South Africa's presidential elections scheduled for 2009.  The ANC will meet to choose a candidate in December.

The labor group endorsement is considered a blow to President Thabo Mbeki.  He is constitutionally barred from running for a third term in office, but had hoped to continue leading the ANC after he stepped down.

Zuma was once seen as a presidential frontrunner, but was fired as South Africa's deputy president in 2005 after his financial adviser was convicted of corruption charges.  Charges against Zuma himself were later dismissed.

Prosecutors have said they may file new charges against Zuma.  He was also acquitted of rape charges last year.  He has suggested the various charges are part of a plot to halt his political career.

Some information for this report was provided by AFP, AP and Reuters.