Voters universally are moved about what impacts them personally. They don't really care about metaphysical issues like constitutional reform.
In Guyana especially, one uses the argument of dhall, roti, and aloo because it affected the ordinary everyday life of every voter.
Ordinary individuals (read Indians) never really cared for the PNC/PPP squabbles much. They just want to be left alone by government. This was the PNC intruding on their personal daily lives. And you close the deal with a reminder of the general racist nature of the PNC.
The PNC escapes this argument in its own base because of racial loyalty.