Ah Huey Long, one of my favorite historical characters for just this reason, he's a good example to look at when you want to point out exactly how perplexing someone can be politically. Nominally a Democrat and in various offices from 1928 to 1935, Long was a strange mishmash of many political identities with an octopus like reach throughout the state. He was a Populist first and foremost, building a strong voter base with the common man, Long had the amazing ability to speak on a level that surpassed religion in a state, Louisiana, that was divided by it politically. He spoke to the common man as if he were one of them, to Catholics, Protestants and African Americans alike (rarely playing the race card to win votes, something pretty astounding for that era). As one reporter put it "Louisiana politics was, in short, a morass of warring factions of an intensity and complexity... matched, in my experience, only in the Republic of Lebanon."

In addition to Long's crazy amount of charisma and populist ideology, there are strong indications of socialist tendencies as well. He pushed for socialist style programs, old age pensions, free textbooks for school children and a massive public works program. In the same breath, he was at first vocal supporter then vocal opponent of FDR's New Deal Programs, instead wanting to support his own Share Our Wealth Program. Something that can't be considered anything but to the absolute Left in politics, desiring to take and disperse the wealth and property of the richest in the US though it had a capitalist edge, as Long wanted to support a strong, consumerist middle class.

On the other hand, Long was a supporter and defender of the Radio Preacher Father Charles Coughlin, someone who originally also with massive public acclaim and a one time supporter of the New Deal. However, Coughlin would turn against FDR heavily after Long's death (moreso than Long did) and Coughlin supported Far Right and Fascist groups in the United States.

Long and his lackeys men controlled the state long after his death and remain a fairly contentious part of Lousiana's history. I think it's fair to say that Long was a Populist or Progressive in the same vein as other leading Populists of the era. Men such as Tom Watson, though Long was able to pull this off without being a Giant flaming racist like Watson was. Long was a continuation of a long strain of "Common Man" politics in the South with a Socialist edge that carried over from before Socialism was dirty word in the American political sphere.