A representative does NOT have to be a member of DSA or any other Socialist or Communist party to count. For example, Bernie Sanders, while not a member of DSA, would count if he were a representative.

"Social Democrats" and other nearby identifications do NOT count. A representative DOES count if they identify as Socialist, even if their policies are more like "Scandinavian capitalism with strong welfare state" than actual Socialism.

Going into the elections, there are two: Alexandria Ocasio-Cortez (D-NY) and Rashida Tlaib (D-MI). As of July 20, by my count, there are at least 11 seats that will have a candidate that would count if they were elected.

The wording "elected US House representatives" in the title means: everyone who was elected, excepting any that withdraw before market close. Of course, they won't take office until January 2027; this market does not seek to capture any changes between market close and the elected individuals taking office.