The European Union mission that monitored Kenya's elections says it is not clear who was actually elected president.
The EU's final report on the December 27 elections released Thursday says there is a "legacy of uncertainty" over the presidential contest.
The observers say Kenya's elections were generally well run and peaceful, but that the vote-counting process suffered from a lack of transparency, undermining confidence in the final result.
The dispute over the presidential election triggered riots and ethnic violence that killed more than 1,000 people.
In an effort to end the political stalemate, President Mwai Kibaki and opposition leader Raila Odinga agreed in February to share power, with Mr. Odinga as prime minister-designate. But the sides remain at odds over the make-up of a coalition cabinet.
A political scientist, Katumanga Musambayi of the University of Nairobi, says international pressure may push the two sides to reach an agreement. But he adds that even if the Cabinet is formed, discord could paralyze the coalition government.
Mr. Kibaki expressed confidence on Thursday that an agreement will be reached.