Who are the three people Bigger and Gus roleplay as while playing white?

Bigger and Gus like to "play white" in Native Son by Richard Wright. We gain important insight into these characters based on the roles they play when they pretend to be white people, of which there are three.
The three characters they pretend to be are the President of the United States, the Secretary of State, and J.P. Morgan. In each role play, Bigger and Gus express and act out their frustration about their place in the society they live in by taking on the role of their oppressors. Each character represents power and resources they do not possess, and how those with power use that power against the powerless.
At the end of playing white, Bigger and Gus laugh, but Bigger's following response afterward is telling and heart-breaking:

"Goddammit!""What’s the matter?""They don’t let us do nothing.""Who?""The white folks.""You talk like you just now finding that out," Gus said."Naw. But I just can’t get used to it," Bigger said. "I swear to God I can’t. I know I oughtn’t think about it, but I can’t help it. Every time I think about it I feel like somebody’s poking a red-hot iron down my throat. Goddammit, look! We live here and they live there. We black and they white. They got things and we ain’t. They do things and we can’t. It’s just like living in jail. Half the time I feel like I’m on the outside of the world peeping in through a knothole in the fence. . . ."

Bigger is expressing his very real and justified anger at the people who hold all the power and wealth, the very same white men they embody when they "play white."