what is the correlation between Jim Casy and the socialist elements of the novel?

Casey was a preacher turned activists. Early on Casey sees the huge inequalities in society. In the camps he sees the suffering at the hands of rich farm owners and bankers. It isa Casey who explores the idea of unions; it is Casey who convinces Tom that the people need to stick together if they want to be treated with dignity. Casey eventually becomes a martyr to his cause.