* Zuma faces major political battle
* ANC general council due to shape rand, mining policy
* Zuma tries to mend strained alliance
By Jon Herskovitz
DURBAN, Sept 20 (Reuters) - South African President Jacob Zuma faces a major battle to shore up his authority this week when the ruling ANC meets to shape policies including on the strong rand and left-wing calls for mine nationalisation.
The meeting of the dominant African National Congress, which opens in the coastal city of Durban on Monday, marks one of the party's most important political events in years.
Zuma faces leaving the National General Council in a weakened position if he fails to hold on to old allies, who want left-leaning economic policies, or to win over some new ones, possibly jeopardising the rest of his term that ends in 2014.
He is already widely seen as an ineffective leader. Zuma's former backers have indicated they may not support him for a second term, while growth prospects for Africa's biggest economy are slowing and a dispute which led to 1.3 million state workers going on strike has yet to be resolved.
"The difficulty for someone such as Zuma is that he has to appease so many different challenges and demands. And being someone who is a consensus-seeking leader, you will always look weak in the process," said Roland Henwood at the University of Pretoria's Institute for Strategic and Political Affairs.
One of Zuma's main tasks is to repair an alliance with the powerful labour federation COSATU, strained by the three-week state workers' strike which was suspended earlier this month, and union accusations of growing cronyism in his government.
Another will be fending off various rivals in the splintered ANC who are lining up their own bids for power in Africa's oldest political party when it enters a post-Zuma era.
Analysts expect Zuma, who is due to address the meeting at about 0800 GMT on Monday, to pay lip service to economic proposals made by COSATU, such as weakening the rand currency from current 2-1/2 year highs. But they also believe he is not forceful or decisive enough to push through any major change.
The calls for mine nationalisation by COSATU and the ANC's Youth League are not likely to lead to any major change for the sector that accounts for about 6-7 percent of GDP, analysts said..
Mine nationalisation would place an enormous financial burden on the country, with the Mail and Guardian newspaper citing estimates of it costing at least 2 trillion rand ($280 billion), more than double the annual state budget.
The Durban meeting lasts until Friday. The next major event on the ANC calendar is in 2012 when the party holds its National Policy Council, which convenes every five years and is used to elect ANC leaders. (Editing by David Stamp)