Unruh's a fascinating figure because he really figured out how to build a party from within a legislature. He essentially forced lobbyists to give money to him, which he would distribute to fellow Democrats facing difficult elections. He understood the importance and power of centralized money and information in a way that few others did before him.
Boyarsky has a great story in there about Unruh's formative years as a student at USC on a GI Bill scholarship. Unruh helped organize a group of working class students, including many veterans, to contest student elections, which had previously been controlled by the fraternities. Then later, he began to work with the frat guys to form the Unity Party, and sought to get himself nominated as the Unity presidential candidate. They held an open convention, and Unruh lost, since the opposition party raided the convention. Unruh learned from this, according to Boyarsky:
Unruh said he learned "that it is impossible to maintain a purely democratic internal structure for a political party no matter how ideologically appetizing that idea might be." After that, and for the rest of his life, Unruh stayed away from meetings unless he had arranged the result beforehand.