A few points in responding to your critique. Yes, you are correct in arguing that it is one thing to criticize mainstream liberal Democrats for compromising their ideals in exchange for corporate campaign money and that it is another to actually contemplate the enactment of a seriously progressive agenda within a system that is fundamentally orchestrated to generate compromise. My succinct counterargument would be that the present alignment/division of partisan forces, on the federal level and across regional constituencies, makes well reasoned, sane compromises, benefiting a vast majority of Americans, impossible. The acrimony over federal health insurance reform(the repeal and replace drama of the GOP relative to the ACA) makes this point quite clear without ever having to consider the crisis of direction in the Democratic Party. The federal government is not the place to contemplate the enactment of any significant progressive policy agendas at this moment in American history. Having said that, it is one thing to promise the moon (single payer now) to voters who have an expectation that you can deliver and another to signal an honest and passionate commitment to progressive ideals whether or not you have the capacity to deliver. The latter, I would argue, is sufficiently representative of Senator Sanders and the character of his appeal to a very large segment of the American general electorate, including many citizens who cast their lot with Trump last November because they believed that he passionately stood for something they did — transcending the gridlock and acrimony characterizing Washington in the interest of solving America’s problems. While I feel certain that Senator Harris would make a supremely competent and astute presidential candidate for the Democratic Party in 2020, I feel equally confident that she would not exude the sense of passionate commitment to address the day-to-day struggles of a majority of the American electorate in ways that, while not being wholly realistic, reach into the hearts of voters. It might be the case that progressives, especially academics, at the fringe of the Democratic Party lack an adequate sense of the necessity of compromise and balancing of divergent constituencies, including beneficiaries of global integration and corporate friendly policies, but I think that there is an innate appeal among a broad segment of the American electorate, inclusive of constituencies that were turned off by Secretary Clinton in 2016, for outright progressives that does not necessarily have anything to do with their policy proposals but everything to do with the way they present themselves.