It is in fact about an election in the tiny city of The Elvira, in Trinidad. The second election ever since the country won independence from the British and universal suffrage.
Its a bit of a farce of the way small town politics works: all the petty grudges and superstitions and tiny power games people play at for scraps of ego, and the futility of the whole process in the end. Harbans wins because he has the most money, not because anyone actually likes him, or because he has plans that can improve the lives of the people of Elvira. In fact, its pretty apparent that Surujpat "Pat" Harbans despises Elvira. But he makes a lot of money on transporting gravel and sand for the town's unpaved roads, and he wants to keep making that money, and prevent the roads being paved.
Naipaul writes the dozens of characters with a cynical wit, though getting used to the vernacular of the dialogue took me a minute. I found this to be a really interesting read from an author who I definitely want to read more from. His later novels, including the one that won the Booker Prize, In a Free State, are apparently less inclined towards humor, though, and I often find it hard to look directly at situations like the election depicted in The Suffrage of Elvira without a layer of humor. If I cant laugh, I just cry.