The answer, simply, is that they have not learned a single thing from Hillary Clinton’s defeat.
Here, in this item produced for National Public Radio’s ‘This American Life’ programme, Ben Calhoun has put together a searing examination – indictment might be a better word – of the current Dem leadership’s strategy to take control of Congress away from Republicans in the 2018 mid-terms.
Go to this link and then scroll down to the item called ‘Fighting Amongst Demselves’ to hear the whole thing.
The Broken Elbow 
THE two dominant parties make far more problems than they solve. Both are like the Catholic Church which spends more focus on Propagation of the faith than spreading the lessons of Jesus. The two Parties focus more on money and reelection than they do on spreading Social Justice.
Jimmy Dore’s amusing take on the same subject. Not one Democrat can explain what they stand for: