Initial reports indicated that the rally was to be held in Uhuru park but it has been cordoned off with heavy police presence.
Supporters trying to access the recreational park have been teargassed.
The NASA rally had earlier contemplated taking the rally back to the Jacaranda grounds in Embakasi but opted for the Olympic grounds which is perceived as the coalition’s stronghold.
Raila Odinga is expected to make a major statement once he arrives at the venue.
The supporters had initially been prohibited from entering the airport upon his arrival Raila Odinga is currently on Likoni road in a convoy escorted by an array of NASA leaders.
It was expected that he would be accompanied by his running mate Kalonzo Musyoka who has been missing in action from NASA rallies to attend to his ailing wife in Germany.
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