Well, were Raila to announce that he was running for governor of Nairobi, I could easily see a situation unfolding where a good three quarters of the Kiambu electorate suddenly shift domicile to Nairobi just to defeat him.
On Raila generally, while I readily acknowledge him to be the single most consequential Kenyan politician of the last 25 years, who, by the way, handily thrashed Kibaki in the 2007 elections by anywhere from 650,000 to 900,000 votes.
That said, I generally fault Raila's abysmal management style and strategic vision when it comes to matters elections; he just can't seem to run a tight ship. In contrast, an overview of the impressive Obama model will give you pointers on the principle rules of electioneering: register, organize and get-out-the vote. It's all about the ground game.