CAPE TOWN (Reuters) - South Africa s President Jacob Zuma suffered a setback on Tuesday when a court ruled that the election of a faction loyal to him in his home province two years ago was invalid. The High Court ruling highlights growing rifts within Zuma s ruling African National Congress (ANC) and could hamper his efforts to ensure his ex-wife Nkosazana Dlamini-Zuma replaces him as party leader and eventually as president.     KwaZulu Natal province, situated on the east coast of South Africa, is the ancestral home of the scandal-prone president and will also command most votes at the ANC s national conference in December, when Zuma will step down as party chief. Zuma loyalists took control of the province in November 2015 at a party conference after ousting former premier Senzo Mchunu, but he filed a court case against his removal, citing procedural irregularities - an appeal upheld by Tuesday s ruling.  The eighth KwaZulu Natal provincial elective conference (in November 2015) ...  and decisions taken at that conference are declared unlawful and void,  Judge Jerome Mnguni ruled. An ANC provincial official told eNCA television channel the KwaZulu Natal ANC leadership would not leave their posts and would probably appeal against the ruling. The party s national spokesman, Zizi Kodwa, said the ANC would study the judgment before taking any further steps. The ruling could further erode Zuma s support base. Zuma, 75, survived a no-confidence vote in South Africa s parliament last month but only after some 30 ANC lawmakers broke ranks and voted with the opposition.  Whoever wins the December contest will lead the ANC, which has ruled South Africa since the end of apartheid, into national elections in 2019, when Zuma s tenure as South Africa s president expires. Tuesday s ruling could hit support for Dlamini-Zuma, a former health and foreign affairs minister, and allow her likely rival, Vice-President Cyril Ramaphosa, a trade unionist-turned-business tycoon, to make gains in the province, analysts said.  Despite court ruling Dlamini-Zuma still likely to be favored in KwaZulu-Natal... but the ruling does allow his (Ramaphosa s) campaign to make more inroads in the province,  said Darais Jonker, Eurasia Group s director for Africa, in a note. Neither Dlamini-Zuma, 67, nor Ramaphosa, 64, have yet stated an intention to enter the race to succeed Zuma in December. Analysts say Zuma s priority is to ensure his chosen candidate succeeds him as party leader so he can complete his presidential term and avoid scrutiny over corruption charges his opponents would like reinstated. The ANC s flag bearer at the national elections usually becomes the country s president, given the ANC s dominance. Daniel Silke, a political analyst, said the judgment could increase factionalism in KwaZulu Natal.  There is now the potential for confusion and disarray within the ANC in the province which could lead to a weakening of Mrs Zuma s position going forward,  Silke said. 