Kibaki, who’s 72 and has health problems, can’t afford to make the same mistake. He and Odinga come from different tribes and are an odd political couple, but Kenya’s future hinges on their rare, cross-tribal partnership. Twice in the ’90s Kibaki ran failed campaigns against Moi. It wasn’t until he successfully courted the charismatic Odinga–promising to create the post of prime minister expressly for him–that Kibaki finally took State House. While he waits for his premiership, Odinga, 58, serves as the minister of Roads, Public Works and Housing. In that post, he holds the purse strings for the vast infrastructure rebuilding that will begin in earnest when the IMF and World Bank resume aid to Kenya as early as July.

During the campaign, both Kibaki and Odinga emphasized the need for tribal unity. But many jaded Kenyans wonder if that lofty ideal can be maintained in a country where ethnic suspicions are intense. Kibaki and Odinga are said to get along, but their backgrounds differ greatly. Kibaki, a respected economist, belongs to the Kikuyu tribe, Kenya’s largest and wealthiest–historically, the elite. Odinga belongs to the long-suffering Luo, who have been blocked from political power for almost 40 years. Moi, who belongs to a third tribe, made his career playing the Luo and Kikuyu against each other. Odinga’s appeal is more visceral: he is revered for his eight years as a political prisoner under Moi, and sometimes feared for his aggressive, populist rhetoric.

Kibaki has vowed to fight corruption and institute the economic reforms needed to revive Kenya’s economy. Odinga says he supports those goals, and he told NEWSWEEK: “We will deal with the insecurity of the country, which is scaring away investors.” But some experts worry that he may drift away from the president’s agenda, especially if Kibaki’s health problems return. The president was hospitalized with a blood clot for a month after his election. “If Kibaki falls ill, you’ll have a power vacuum and Raila will assert himself,” says World Bank senior consultant Joel Barkan. He says that Odinga “wants power for himself and a better shake for the Luo.”

Sometime this spring, Kenya will write its new Constitution, and Kibaki will have to decide how much executive power he wants to cede to the new premier. No matter what, Odinga will be watched. Kenyans are counting on him to work with Kibaki, and to stay clear of any inclinations to settle scores. “The population told the leadership in the election, ‘Please unite. We know what happens when we don’t unite’,” says Hampshire professor and Kenyan political expert Frank Holmquist. Odinga helped elect his boss by preaching that message. The question now is, does he believe it?