There is a growing schism in the Democratic Party between its two poles of influence in the age of social media: the younger, urban, and more left-leaning people who carry out a daily and often pestiferous political dialogue on Twitter, and the older and more traditionally liberal-to-moderate people who make up the actual backbone of the party across America. If there is a division within the party that will bring it to ruin in 2020, this is it. Both factions reflect the seriousness of the fight to define the party anew as it crawls out of the Clinton “New Democrat” era in search of some as-yet-unnamed identity. I think both more or less agree on the problems: the recent failure of American capitalism to provide the more broadly shared prosperity we once enjoyed, the crisis facing our democracy and institutions under Trump, and the depraved authoritarianism of the Republican Party. But Democrats are quite divided on the solutions.
This view from the center left expresses the view that 1) more Democratic voters are liberal and moderate than left leaning and 2) that the potential for an acrimonious primary season could undermine the ultimate party candidate and provide an opportunity for Trump and trolls to exploit the division. He does not mention the role of money and media which will undoubtedly be arrayed against the left.
Whomever you support for president and whatever your politics you must recognize the reality of this fear and think about what you can do to minimize this risk.