(Long term thinking on US party politics. In the short term we must come together and resist.)
Jim Wright complains that the Democrats are not unifying. I think the place to look for reasons is where the Democratic leadership stands. With the Republican turn to right-wing extremism, both conservatives and liberals have joined the Democrats, leaving the party with a conservative wing and a liberal wing, and if they satisfy one, they cannot satisfy the other. This results in a party which cannot articulate a vision which will energize voters.
"The left" is not – cannot be – an organized faction in US politics unless the US political order changes. Bernard Sanders, the unexpected leader of the US left who emerged in the 2016 election, acknowledged this and, after losing the Democratic nomination, supported and campaigned for Hillary Clinton. As far as I can tell, most of his supporters followed him; the vocal Sanders left appears to be a small minority.
At this point, it seems to me we are in a space of shifting coalitions within the parties. Outside of the Republicans, young people and older women are the two largest demographic factions, and these are at loggerheads. Inside the Republicans, the heat is rising. So far, Trump still has his support, but it is possible that will fracture, as Trump fails to deliver. There is a huge amount of money on the radical right side, however, and there are many people who desperately want a return to the conditions of their youth, and that is not possible.
As to emergent groups, I would keep an eye on Indivisible, which appears to be the most politically effective of the loose coalitions that emerged in the wake of the vast failure of 2016. Sanders Our Revolution is also around and is fielding candidates, and their policy wing, the Sanders Institute, is finally, finally beginning to articulate a moderate leftist vision for United States in the 21ˢᵗ century. So far, I'm not seeing anything that strongly impresses me from either of the Sanders groups, but it is early yet.
I would like to say something kinder about the Democratic leadership, but it appears to me to be working terribly hard to lose more elections.
Finally, I remind everyone yet again that all of this is long-term thinking. In the short term, we must resist.