The situation in fact is that the DP is split down the middle between the Socialist and the Non-Socialists, while the latter faction is again spilt between the leftists and moderates, So the end result is a heavily leftist and socialist presence in both the House and the Senate,
The more moderate members of the DP in the House and the Senate are in fact ineffective and is just about tolerated as a faction because they really have no say in what is really the policy of the DP. They are in turn undermined by the Socialists who are trying to find candidates opposed to them in the DP primaries. The real fact is that there is a fightback by the minority DP members made out to be "moderates" - irrespective of whether they are indeed moderates or not is debatable - but the fact is that Socialism is the base of the present DP policy and that will not change at all, irrespective of who turns out to be the candidate against Trump in November.
The only thing that seems to hold the DP together as a political party is their joint hatred of Trump. Because of the Internal factions the Party has no cohesive policies and that will not change in future. The mismanagement and gross maladministration in California, New York and Illinois will become the norm in the USA as a whole when they get into power,
That make the present debates between the various DP candidates in the primaries so weird. The debate is not about policy - it is entirely based on who could stop Trump from being re-elected. It is like a comedy show more than a political debate. They really have nothing to debate because they lack a cohesive policy approach. So it looks more like a catfight as to who should oppose Trump. The only honest one amongst the whole lot is Sanders - at least he stands for something he believes in - the rests have no policies they really stand for and only promotes their own interests in getting into power, What they would do if they get into power is not an issue.