In 1926, the California Gubernatorial Election was an interesting blip in American history. Lieutenant Governor C. C. Young, a Progressive Republican, defeated the more Conservative Incumbent Friend Richardson in the Primary while Author of "The Jungle" Upton Sinclair got close to 5% before becoming the gubernatorial nominee eight years later and just barely losing despite his EPIC (End Poverty in California) plan. So, what if Sinclair barely wins the Dem Nomination, Richardson barely defeats Young, and Sinclair barely wins the Governorship and then wins re-election in 1930 against James Rolph with a very Pro-EPIC State Legislature behind him. In 1932, Sinclair, not Roosevelt, is the Dem nominee and he wins and beats Hoover and as President pushes for major racial equality and a national enforcement of EPIC, relying on Northern Liberal Republicans instead of the South. Who is Sinclair's running mate(s), what is the effects of his E. P. I. C. plan nationally, how does his Presidency effect the South and the two major parties, who does he appoint to the Supreme Court, and finally what would WW2 be like with a President Sinclair in charge when it happens?
Well, there's still a big gap between "getting 5% in on state" as you said, and "being elected POTUS". A very big one.
He only won 5% of the vote in 1926 likely because he was the Socialist Party Nominee and not the Democratic Nominee for the Governorship in 1926. Here, he is the Democratic Nominee for Governor of California in 1926 and wins against the Conservative Candidate and wins Re-election in 1930, making him a frontrunner for 1932.