There is socialist candidates ?
We have lots of "third" parties, but their candidates are rarely invited to televised national debates or make significant news.
In swing-States, third party candidates will sometimes tell their supporters to vote for the preferred major candidate. Better to have a X than a Y in office, since we have "no hope" of winning.
For example, Saede is from New York (based on previous post). Voting for a Socialist in New York is unlikely to take critical votes away from the Democrats. Last election, I voted in Texas and my vote for a Libertarian candidate did not take critical votes away from the Republican. If we voted in Florida or Ohio, our choices would be seen as more important because candidates win in those states by very narrow margins.