I think it is inevitable that leftist forces in the US would be divided, if not balkanized, to some extent. Among the full range of people who are committed to social and economic equality and ecological justice - i.e. to some variant of a leftist vision of a decent society - it will always be the case that some will be more focused on egalitarian economic issues, others around the environment and climate change, others on US imperialism, militarism and foreign policy, others on race and gender equality, and still others on sexual identity.