KTN television said Raila Odinga had 3.7 million votes, compared with 3 million for Kibaki. Ngari Gituku, spokesman for Kibaki's Party of National Unity, or PNU, said that the party's mood was anxious but that Kibaki was expected to close the gap as the counting continued and votes from his central Kenya stronghold were included.
Early estimates put voter turnout at 70% of Kenya's 14 million registered voters, the highest since multiparty elections were reintroduced in 1992, in what some analysts saw as a sign of growing voter confidence in elections.
Democracy often comes in a poor second to the dominance of the ruling party or election rigging across much of Africa. But U.S. and European observers and local news media praised the balloting despite chaos at some polling stations, delays and opposition accusations of vote fraud.
The Daily Nation newspaper said the efficiency and independence of the elections "should be the envy of the rest of Africa."
But some analysts cautioned that Kenyan democracy still has a way to go, with rampant vote buying in the lead-up to the poll and many people voting along tribal lines.
Both the PNU and Odinga's Orange Democratic Movement criticized the slow pace of the count from the presidential and parliamentary elections Thursday. Television and radio stations were the quickest in releasing voting figures.
Official numbers from 68 of Kenya's 210 constituencies gave Odinga 1.6 million votes to 1.2 million for the incumbent.
Kibaki ran on a record of 5% average annual economic growth and instituting free, universal primary education. Opponents said he failed to deliver on his promise to crack down on corruption, a key issue for Kenyans.
Odinga, a former political prisoner who campaigns in a red Hummer, has promised to build roads and schools and distribute Kenya's gains to the poor.
At Odinga's party headquarters and in his stronghold in the Nairobi slum of Kibera, his supporters were increasingly confident.
One supporter, Anderson Ooko, 32, wearing the trademark orange cap of Odinga's movement, was frying fish to sell in a large pan on the roadside. He said it was clear that Odinga would beat Kibaki.
"We know we are winning, but just tell them to dare steal our votes, we will show them dust," he said.
A 40-year-old vegetable seller and mother of four, Josephine Adhiambo, was just as sure of victory. "Tell Lucy Kibaki [Kenya's first lady] to start packing," she said, laughing. Lucy Kibaki was caught up in controversy recently when she slapped an official for mixing up her name.
About one-third of the members of Kibaki's 32-person Cabinet lost their parliamentary seats, including Vice President Moody Awori, according to television.
Kenyan environmentalist and Nobel Peace Prize laureate Wangari Maathai also lost her seat, television reports said.
Peter Wanyande, a member of Odinga's strategy team, said his party had so far picked up 81 seats in the 210-member parliament, compared with 22 for Kibaki's party.
"This government has been involved in very serious cases of corruption, and it's usually ministers who are behind these cases of corruption, so their rejection is a demonstration of the voters of this country that they are unhappy with the manner this government has handled corruption," he said.
Political analyst Patrick Lumumba, a well-known constitutional lawyer and candidate for parliament from an opposition party, said there had been wholesale bribery to get voters to follow tribal lines, and called for much more voter education.
"If democracy means holding periodic elections every five years, then we can say it is vibrant," he said. "But I personally want to believe democracy is much more than people voting simply because they have been given money to vote for their tribe."
Special correspondent Soi reported from Nairobi and Times staff writer Dixon from Johannesburg, South Africa.