Kenya's veteran politician Raila Odinga has been confirmed as the main opposition coalition's presidential candidate for August's election.
Mr Odinga, 72, is set to face incumbent President Uhuru Kenyatta, the man who beat him in 2013.
This will be the fourth time Mr Odinga runs for president.
He also ran in the disputed 2007 poll. The violence that followed led to the creation of a unity government in which Mr Odinga served as prime minister.
Mr Odinga will represent the National Super Alliance (Nasa), which is a coalition of the country's main opposition parties including the candidate's Orange Democratic Movement.
Odinga v Kenyatta round two, Dickens Olewe, BBC Africa
Raila Odinga's nomination is not a surprise.
He has performed better than his rivals in opinion polls and has shown that he has wide support beyond his ethnic base in western Kenya.
Going into his fourth election, Mr Odinga is rehashing a strategy used in the 2002 campaign when opposition parties united to defeat Kanu, the party that brought Kenya independence.
The coalition that won that vote did not however survive as former President Mwai Kibaki reneged on a pre-election deal.
To try and avoid this, the Nasa coalition has unveiled a power-sharing structure involving the party leaders.
During Thursday's rally Mr Odinga called himself "first among equals".
The announcement was made at a rally at Uhuru Park in the capital, Nairobi.
Thousands of opposition supporters turned up and live video footage from the rally showed them breaking out into wild cheers as Mr Odinga's name was read out.
His running mate will be former Vice-President Kalonzo Musyoka.
In a statement, President Kenyatta described the Nasa nominations as "about giving jobs [to the politicians] instead of the millions of Kenyans who need jobs".
Mr Odinga is trying to run on an anti-corruption message and is also emphasising that he is the candidate of national unity, says the BBC's Dickens Olewe.
President Kenyatta says that Kenya has achieved a lot of economic development under his government and he has managed to increase opportunities for the country's large youthful population.