JOHANNESBURG, Sep 22 (Reuters) Former Deputy President Jacob Zuma today said he was not campaigning to become South Africa's next president, following the collapse of a graft case against him.

Zuma's supporters, including trade unionists, communists and many rank and file members of the ruling African National Congress want him to replace Thabo Mbeki as South Africa's president in 2009.

But Zuma said at a news conference: ''I am not in a race, I am not campaigning.'' He said he would respond only if the African National Congress asked him to stand for its leadership.

Zuma, a hero of South Africa's liberation struggle, had been seen as frontrunner to succeed Mbeki in 2009 until Mbeki fired him as deputy president last year after a judge found he had a ''generally corrupt'' relationship with his financial adviser.

Zuma's political fortunes changed again this week when another judge dismissed corruption charges against him.

Mbeki's office has so far declined comment on Wednesday's court ruling, which stopped short of completely dismissing the case against Zuma -- leaving open the possibility the corruption charges could be refiled.

But South Africa's powerful COSATU labour union passed a resolution yesterday calling on Mbeki to reinstate Zuma as deputy, a position that puts him in line for the presidency.

Reuters DKA VV1555