20091201

WINDHOEK (Reuters) - Namibia's ruling party was heading on Tuesday for a big election win but results so far showed the two-thirds majority which gives it the power to change the constitution is under threat.

Initial results from nearly 92,000 of 1.18 million registered voters in the arid state show the South West Africa People's Organisation, a former guerrilla movement that led the country to independence in 1990, leading with 64 percent.

SWAPO is widely expected to secure another five-year term following last week's presidential and parliamentary elections. But the two-thirds majority that it has held since 1995 is less certain due to the emergence of a stronger opposition party.

The electoral commission said the final results of last week's voting would be published on Tuesday but counting has been subject to a series of delays.

SWAPO's sternest political challenge yet comes from the Rally for Democracy and Progress (RDP), which split from the ruling party in 2007, and holds 12 percent of the votes cast.

"By any standards, it will be a landslide victory ... and although it's too early to say if SWAPO will get the two-thirds, the RDP, by Namibian standards, will be a strong opposition," said Graham Hopwood, director at the Institute for Public Policy Research.

Namibia's politics have been dominated by SWAPO since independence and opposition parties struggled to make an impact.

Altogether 72 National Assembly seats up for grabs in Namibia, one of Africa's wealthier states because of diamond and uranium exports. In 2004 elections SWAPO won 55 seats and needs to secure 48 seats to retain the two-thirds majority.