This page gives a list of 58 members of the 'Congressional Progressive Caucus' (soon to be 57; Cynthia McKinney's in there), who the DSA claims is working with them; but there's no mention of any members of CPC being also members of DSA.
Let's be careful about what we're claiming.
The direct link to the "Progressive" Caucus conveniently disappeared from the DSA web site just before the 2000 elections. I guess the heat was getting uncomfortable for the Congressional Commies by then.
No wonder they want to regulate the internet.