None of them would have been elected if they did. It was the Depression. Roosevelt was going to win by a landslide. They won what conservative sentiment was out there and there wasn't much of it.
Phyllis Schlafly had the idea that a more conservative candidate could have beaten FDR or Truman, but her man, Barry Goldwater, did almost as poorly as Landon and considerably worse than Willkie or Dewey in the popular vote, and that against a much less popular opponent than Roosevelt.
But you do slander Hoover, who articulated about conservative a vision for America as anyone after he left office. He could form and express such a view when circumstances commanded it. It didn't win over most Americans even then, but he wasn't lacking in intelligence and showed great commitment to conservative principles in his later years.
And they all lost to the second worst communist president the USA ever had.
You either are a communist or you aren't. Roosevelt (and whoever the other president you're talking about is) had their faults, but they weren't communists or Marxists. I don't disagree with what I think you're trying to say, but surely there's a better way of phrasing your thought than this, especially after what happened yesterday.
Hoover's entire adult life, up through his presidency, was that of a liberal progressive, big government, globalist, command and control, anti-freedom, Republicrat; endeared to both the liberal Democrats, i.e. Wilson, and the east coast liberal Republican swine.
Like the RINOs of today, Hoover wanted to pretend that the "labor" part of the "land, labor, and capital" as in the means to production in a free market economy, should be free, or at least dirt cheap. As we can clearly see now, the "free and cheap labor" plot is a death knell to a functioning, sustainable economy. The theft of citizens' labor, along with corruption in every other corner of society, eventually leads to massive loss of returns on capital and land as well. The measuring stick for our current such fiasco is a whopping $15 Trillion national debt.
Absent corruption and manipulation, there is a market price for labor of all types, driven by supply and demand, just as Adam Smith described for all goods, services, and resources.
Absent corruption and manipulation, there are national boundaries, within which free market principles can work to their greatest potential. International trade by such a free market nation should be negotiated nation to nation, to the benefit of both nations, not to the benefit of a few corrupt people and to the detriment of the majority of citizens. Adam Smith's book is short-titled "The Wealth of Nations", not "The Wealth of a Few Globalist Commie Crooks".