By ANJAN SUNDARAM
The Associated Press
Sunday, August 13, 2006; 7:55 PM

KINSHASA, Congo -- Electoral officials slowly counting votes from Congo's landmark presidential election said Sunday that support for incumbent Joseph Kabila has slipped to just above 50 percent, increasing the likelihood of a runoff.

Less than a quarter of the ballots cast from the July 30 vote have been counted. Unless one of the 33 candidates wins the majority, the two top vote-getters will face each other in a second round of voting.

With 4.7 million of some 20 million votes counted, Kabila has received 51 percent of the vote, compared with 19 percent for Jean-Pierre Bemba, an ex-rebel leader and vice president in the Central African country's postwar national-unity government.

The latest count included about a million more ballots than Saturday's figures, which had put Kabila's share at 53 percent, helped by a rash of ballots from the east where support for the transitional leader is strong.

Many of Sunday's additions came from the Equateur region where Zanga Mobutu, son of Congo's last dictator, Mobutu Sese Seko, had a strong showing. Mobutu has received at least 2.7 percent of the vote, though a more specific figure was not available.

Others who have received at least 2 percent of the vote included Pierre Pay Pay, a longtime ally of Mobutu Sese Seko, Harvard-educated Dr. Oscar Kashala and 80-year-old Antoine Gizenga, most showing strength in their native provinces.

No firm results have been posted from the capital, Kinshasa, where Bemba is believed to have strong support among the sprawling city's 8 million people.

The election _ Congo's first multiparty presidential vote in more than four decades of war and unrest _ was seen as a chance to establish democracy and peace.

On Friday, authorities arrested six electoral workers accused of tampering with the count as 19 candidates joined in a bloc to denounce the vote as fraudulent and call for a fresh vote, spokesman Roger Lumbala said.

The specter of Congo's population rejecting the election worries foreign diplomats, who say the vote's legitimacy is crucial to swinging Congolese behind their first democratic leader since 1961. Many international observers noted irregularities in the voting and protracted and chaotic counting, but none so far considered serious enough to affect the outcome.

In all, about 80 percent of Congo's 25 million registered voters _ some 20 million people _ cast ballots in the presidential and legislative election. Congo has 58 million people.

A preliminary countrywide tally was expected to be announced Aug. 20, and a final tally Aug. 31.