Up to half the supporters of South Africa's ruling African National Congress feel uneasy with the party and some could defect to the opposition before the 2009 general election, a survey showed.

The ANC has dominated since the end of apartheid in 1994, usually winning two-thirds of the vote in national elections. But it has been hurt by a leadership battle that led to the removal of Thabo Mbeki as South Africa's president in September.

A group of Mbeki loyalists launched a new party, the Congress of the People (COPE), earlier this week.

A total of 42 percent of those who identified themselves as ANC supporters said they were uneasy with the infighting and one-fifth supported the idea of a faction forming a new party, the Ipsos Markinor survey showed.

"It is quite clear that approximately between three and five in every 10 ANC supporters are not very comfortable with the ANC at present and that around 15 to 20 percent could act on this unease and consider defection to other political parties," the research firm said in a press release on Thursday.

The poll showed the ANC, now led by Jacob Zuma, with 62.5 percent of support of the 3,500 eligible voters polled, down marginally from a year ago, but shy of the two-thirds it would need to make changes to the constitution.

The next election is expected in March or April, 2009.

The Democratic Alliance, the country's main opposition party, saw its support dip to 11.2 percent from 13.3 percent a year earlier.

The poll was conducted in October before the launch of COPE, which is seen as the first real challenge to the ANC's 14-year hold on power and possibly the biggest reshaping of the political landscape since the end of the apartheid era.

"It seems likely that through a combination of attracting support away from the ANC and opposition parties, COPE should be able to win at least 10 percent of the votes," said Eurasia Group analyst Mike Davies.

"Although this will not threaten the ANC's position as the ruling party, it is likely to bring the ANC below the two-thirds majority required in parliament to pass constitutional amendments. It is also possible that the ANC might lose control of one or two of the provinces."

COPE, led by former defence minister Mosiuoa Lekota, has not released its election programme, but it has signalled that it will adopt centrist, pro-business policies similar to those pursued by Mbeki during his nine years in office.

The business community, traditionally supportive of the ANC, fears that trade unions and the South African Communist Party have too much influence in the ANC. Zuma won strong support from the left when he beat Mbeki for the leadership in 2007.

While vowing not to make dramatic changes to policy, Zuma could face growing pressure from his allies in the COSATU labour federation and SACP to do so, especially if the ANC's pro-business wing defects en masse to COPE.

Mbeki has neither condemned nor supported the new party.