Huey Long got a pretty bad rap following his death on the fascism count. Partly due to his populism and partly just a product of that charged decade, the idea of Long as some sort of American Hitler (a la It Can't Happen Here) stuck for quite a while. It wasn't really until the 1970s that this was challenged. Following T Harry Williams, the tendency has been to cast Long as merely a machine politician - that very American of occupations. His 'dictatorial' control over state legislature and institutions was the product of his success in such a role, rather than something particularly fascist per se. The charges of fascism have tended to stem more from the trappings of the Kingfish - the adulation that he inspired, his innovative campaigning means, his very public persona - than anything in his programme proper. Long himself dismissed the accusations and was publicly disdainful of comparisons to Hitler.

Which is not to say that Long was a democrat - he had no qualms in perverting democratic mechanisms to enact his policies - but this fits comfortably within American political traditions without having shoehorn him into a fascist mould.

If later historians have generally played down accusations of fascism, the reverse is probably true of the issue of racism. In his own time Long was seen as being relatively tolerant for a Southern politician - he rarely played the race card and his economic programmes tended not to distinguish between black and white. Today, of course, post-Civil Rights era, 'relatively tolerant' no longer seems quite so impressive. Long was a segregationist who had no interest in breaking down Jim Crow and was happy to race-bait when it bought him votes. So yes: I'd argue that Long was a racist but a relatively mild one (if that is possible) by the political standards of his time and place.

As for becoming president, in 1935 the Kingfish had a strong national profile (with polls putting support for him at around 10% across America) but no coherent policy platform, no real organisation outside of Louisiana (the Share Our Wealth Society hardly qualified as this) and no support from the political establishment. More importantly, his support base was to the left of Roosevelt; the latter could, and did, shift slightly to the left to occupy this space. You can construct a counterfactual in which Long splits the Democratic vote in 1936, therefore allowing him to run as a New Deal candidate in 1940. Possible? Yes. Likely? I don't believe so.

Sources To my mind Williams' Huey Long remains the definitive biography of Long. Richard White's Kingfish is more recent but doesn't, I feel, add much. Plus Berlet et al, Right-wing Populism in America

I can't speak to fascism or his presidential chances, but Huey P. Long was certainly at least as racist as any white southern politician at the time.

One illuminating anecdote: when the Louisiana Legislature allocated funds to build a black college (now Southern University) next to Louisiana State University, Huey Long didn't want a black school "tarnishing" his favorite (white) school. So before construction could begin, he ordered prison labor to dig and create a lake on the proposed site. The shallow "University Lake" still exists next to LSU today.

The new lakes made the construction of the black college prohibitively expensive so it was relocated. The new site was on a bluff overlooking the Mississippi River north of Baton Rouge and is one of the best views in the city. Southern University is still located there today.