Both men had on Sunday appealed for calm as the wait for the final results of the August 9 vote dragged on.
Kenya's Deputy President, William Ruto and Raila Odinga are in a tight race as the electoral body in Kenya continues to count election results.
As at Monday, Ruto was leading with slightly more than 51 percent of the vote against 48 per cent for Raila Odinga, based on official results from more than 80 percent of constituencies, according to a tally published by the Daily Nation newspaper.
Both men had on Sunday appealed for calm as the wait for the final results of the August 9 vote dragged on.
Polling day passed off largely peacefully, but memories of vote-rigging and deadly violence in 2007-08 and 2017 still haunt Kenyans.
The Independent Electoral and Boundaries Commission is under intense pressure to deliver a clean poll in a country regarded as a beacon of stability in a troubled region.
Results must be issued by Tuesday at the latest, according to Kenya’s constitution.
Ruto, 55, is deputy president but is effectively running as the challenger after outgoing President Uhuru Kenyatta threw his support behind his former foe Odinga, the 77-year-old veteran opposition leader making his fifth bid for the top job.
Kenyans voted in six elections, choosing a new President as well as senators, governors, lawmakers, women representatives and some 1,500 county officials.
Turnout was lower than expected at around 65 per cent of Kenya’s 22 million registered voters, with observers blaming disenchantment with the political elite in a country battling a severe cost of living crisis.
The IEBC had faced sharp criticism of its handling of the August 2017 poll, which in a historic first for Africa was annulled by the Supreme Court after Odinga challenged the outcome.
Dozens of people were killed in the chaos that followed the election, with police brutality blamed for the deaths.
Kenyatta went on to win the October rerun after a boycott by Odinga.