Astonishing that the question "What party did Eugene V. Debs represent " has the least number of right answers, since the number of parties in the US should be limited...
For non US-citizen like me still sort of difficult, but since US-Americans are most likely the largest group of people here...
It doesn't astonish me... I didn't get it. To the extent that third-party candidates get any coverage it's often due to silliness or covered as a sideshow; there's very little organized party activity in the public eye even among more well-known third parties like libertarians. Most third-party candidates in national elections run as or are covered as "independents". Socialism has been such a dirty word in American politics for so long that it's just not something people now would be that aware of. Sure, everyone sees the Constitution party on their ballot or whatever but it's such a minority activity it doesn't make much impact.
Even a weirdo outsider like Lawrence Lessig, who I supported, ran as a Democrat.
The Socialist party got some attention in the early 20th century, gaining a few percent of the popular vote, but is almost non-existent today. They are only on the ballot in a few states and only get a couple thousand votes across the entire country. There's basically no news coverage of the Socialist party and most people wouldn't know that it exists.
For non US-citizen like me still sort of difficult, but since US-Americans are most likely the largest group of people here...
Even a weirdo outsider like Lawrence Lessig, who I supported, ran as a Democrat.