The NDC is expected to be Raila's defining moment since his ODM party is set to have a joint session with Jubilee, after separate meetings, that will see him endorsed as Azimio La Umoja presidential candidate. Guests started streaming in as early as 6 am.
A host of leaders are expected to attend the NDC.
President Uhuru Kenyatta will lead his Jubilee party in the NDC.
According to the designated sitting arrangements at the venue of the function, seats have been reserved for Raila, Wiper leader Kalonzo Musyoka, KANU's Gideon Moi, Narc Kenya Martha Karua and UDP's Cyrus Jirongo.
The OKA's invitation to the meeting comes a day after the Wiper leader announced entry into the Azimio la Umoja.
Kalonzo said they have officially kicked off a structured dialogue that will see them sign grand coalition dubbed Azimio- One Kenya Alliance.
The coalition agreement between the parties will be signed on Monday.
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