East African time (0300 GMT).
Why are Kenyans nervous about the election?
Former President Barack Obama, who has largely stayed silent since President Donald Trump took over in January, opted to speak out about the hotly contested presidential election scheduled for Tuesday in Kenya, where voting in recent years has been followed by violence.
Thousands of worldwide observers have been monitoring the vote amid fears of a repeat of the violence that plagued the country following elections a decade ago.
If no victor is declared, the election will go to a runoff, which would be a first in Kenya's history.
In Kenya's Kisumu city, voters have different views about the possibility of violence if there is a dispute over the results of the presidential election. There was no violence that time, but the result was controversial because Kenyatta was then under indictment by the International Criminal Court for crimes against humanity over his alleged role in the 2007 violence.
The last election in 2007 was marred with violence with more than 1,100 deaths and 600,000 others were displaced.
After more than a month of negotiations, former United Nations Secretary-General Kofi Annan mediated a power-sharing agreement in February 2008 that was signed by both leaders.
Kenyan are voting on Tuesday in the elections pitting Odinga against President Uhuru Kenyatta.
The election commission has said that about 25% of polling stations will not have network coverage, meaning officials will have to move to find a better signal and transmit results by satellite phones. Even if violence is avoided at a national level, it could nonetheless marr local races for governorships and parliamentary seats, some of which are as hotly contested as the presidency.
Obama, whose father was born in Kenya and who still has a family in the African country, issued a long statement on Monday calling on Kenyan citizens as well as its leaders to leave fear and division behind, reports Efe news. Urban centres are up for grabs, although Odinga now controls Kenya's three big cities. Mr Odinga's campaign has focused on the high price of food and the fight against corruption.
Eight candidates will battle it out in the presidential race, 1,892 candidates will be seeking to be elected as Members of Parliament, 11,857 candidates vying for Member of County Assembly, 211 gubernatorial candidates, 256 senatorial candidates and 299 seeking Woman representative positions. This measure is designated to force powerful groups to build alliances with smaller tribes. Officially, election authorities have up to a week to declare the outcome, reported Reuters. In 2013, Odinga lost again to Uhuru Kenyatta. Odinga is associated with the Luo voting bloc, which has never produced a head of state.
The two main candidates in this election are well-known to Kenyans.
Although the country remains dominated by tribal politics, reforms aimed at fostering ethnic inclusion are bringing some small, gradual changes.
"I am encouraged to see the spirit of the Kenyan people every day; the spirit of architects laying the foundation for our nation's future prosperity- across every corner of our country".