So let me try once again:
For Marxists and other radicals who were active in the unions and allied social movements, Carrol's statement above was never the end point but the start of any serious discussion about the Democrats and liberal capitalist (ie. social democratic) parties abroad. The question was never whether these parties were political "enemies" but rather how to displace them. When the far left was organized and growing in small (and not so small) mass parties, it was possible to conceive that these would one day supplant the bourgeois reform parties. Even then, participation in these larger organizations, where possible, was encouraged in cases where the far left was considered still too weak to serve as a viable pole of attraction on the outside.
Carrol believes he is unique in insisting on a boycott of the Democrats. But shunning the Democrats and other mass reform parties in favour of more stimulating intellectual activity in tiny study groups or political sects has been characteristic of left-wing intellectuals for generations. Such abstention is more understandable today when there is no longer a vital working class political culture nor the opportunity to participate in a significant socialist movement within it, but it remains sadly self-deluding to pretend that such abstention constitutes meaningful political action in Bloomington or elsewhere. Carrol can at least take comfort that he is not as alone as he commonly supposes. His views are fairly typical, it seems to me, of many on the now mainly campus-based US far left.