A Patron is the protector, sponsor, and benefactor of a Client in the Empire. A patron represents a block of Clients. Powerful Patrons have most influence on their Senator who represents their interests in the Senate. Patrons can move their block to a different senator if they think the senator doesn't represent the views of their clients. Senators can lose Patrons quickly if their actions are unpopular, but a Senator sets tax rates and healthcare for all those that support them, so can effectively bribe Patrons to ally themselves with them. Every Patron has a right to be represented by a Senator.
A very popular Patron can petition to become a Senator if he or she thinks they could represent more Imperial Citizens than one of the least popular Senators. That less popular Senator the petitioner chooses to target has the opportunity to rally support against the challenger for seven days, but as does the popular Patron, and at the end of that period a decision is made based on their support, and that Patron cannot petition again for 1 Earth year if they are unsuccessful.