There are two political approaches open to the Democrats; circle-the-wagons and cut-your-loses. Normally, they circle-the-wagons. It is really extraordinary that they chose the latter course. She really is political poison. You have to really step in “IT” to become poison. She not only stepped, she wallowed.
All the clues are in the article. “Grass-roots” is a code-word meaning the Sanders wing of the party.
For the Dem politicians WS’s only mistake was not that she lied and cheated—it is that she got caught lying and cheating.