A few Leftists are taking advantage of the space opened up in the national dialogue by the Bernie Sanders campaign to remind people of America's Socialist history and try to open the space wider, as Lawrence Wittner does in an article in Common Dreams.
Others are critical of Sanders' ties to the Democratic Party and worry that the way democratic socialism is being portrayed down peddles and dilutes what socialism means, and accuse Sanders of "sheepdogging," i.e., of fulfilling the function, intentionally or not, of simply bringing the Left back into the fold of the Democratic Party. Jesse Jackson and Dennis Kucinich were accused of that, too.
There's something to both points of view, but both are lacking, too. I've on many occasions written about the Socialist history of the US, with similar ends in mind. But Socialism isn't something that can be grown or killed. It's arises out of human nature. The societal shifts in the past century that led to the mass movements that brought it into American politics and into the leadership of European governments may have been planned for and eagerly awaited by Socialists, but they occurred as natural reactions to peoples' discomfort and pain and abhorrence to Capitalism and/or feudalism as the case may be. The cooperative economy of Socialism is second nature to humans. Every member of the species would come up with the same idea. It's who we are. It's genetic.
But we're also inherently, genetically, what leads to Capitalism; and to its current excesses and the apocalyptic dead-end into which it may be headed, as frighteningly described by Henry Giroux in Truthout magazine.