In the beginning of the 20th century, a wave of socialism swept through Europe. Socialists started to win over the mind of the common man, were elected to public offices, and — when all else failed — overthrew governments, for better or for worse. The residue of that is still seen in Europe today.
In America? Not so much. But it wasn't for lack of trying: multiple socialist parties sprung forth, just like they did in Europe. For whatever reasons, they didn't take hold. (There was A LOT of infighting, for one. Also, socialist opposition to World War I led to the First Red Scare, which helped put down the movement.) As for elected officials? They were far and between.
Two did manage to get elected to Congress, both Jews: Victor Berger of Wisconsin, and Meyer London of New York. But let's just say that their stays in Washington weren't exactly effective.
Reading over London's story, one can't help but feel his despair. For some, he was too radical; for other, not radical enough. Vehemently anti-war, the only House member to vote against the Sedition Act, he was nonetheless criticized by his constituents for choosing to support the war effort. Even Jews couldn't agree: for some, the problem was that he wasn't religious, for others, that he was too liberal.
So, after London was voted out in 1923, that was it for Socialists in the US government. For better or for worse...