What is the fraud? The party likely did what it was allowed to. The ethics and deceit of leadership is another matter entirely.
The fraud is clear on many levels.
Here are two easy ones:
1. The ballots are printed with choices, the primary voters are led to believe they are the choosers when in fact they are not allowed to choose.
2. The primary voters are asked to donate to the candidate of their choice to assure their choice is adequately financed and supported when in fact the money that is handed over is never intended to do such things.
In the first case, the actionable cause of action is fraudulent, deceptive advertising. In the second case, the financial support is solicited as a fraud.
The actual complaint is here:
http://jampac.us/wp-content/uploads/2016/06/1-CLASS-ACTION-COMPLAINT-6-28-16.pdf
And the case documents are here: