The Best Guide for the Perplexed Progressive in 2020 is 2016

The current round of presidential debates is packed with plans, programs, promises, claims and counter-claims. The question, as always, is which candidates are we to believe. The closer we get to an election, unscrupulous candidates tailor what they say to what the voters want to hear. The problem is separating the flimflam pols from the honest ones.
Even more problematical, how are we to distinguish the politician who is comfortable with the loftiest words but lacks the courage to fight for them? Ideas are a dime a dozen, and the best ones in the political realm are simple. They do not require an Isaac Newton to formulate them, let alone recognize them. A child who can say, “The Emperor has no clothes,” will do just fine as long as the kid has the courage to say it. Testicular or ovarian fortitude, as the case may be, is essential
In 2020 as progressives look at the Democratic Party candidates, how are these questions to be answered? For 2020 there is a simple answer. Just look at 2016.
2016 was widely recognized as the year of “populism,” more adequately described as the year of revolt against the political Establishment – in both Parties. The Democratic Primary in 2016 was a battle of progressive forces against the Democratic Establishment, and the battle lines were clearly drawn. Those lines remain much the same as we approach 2020.
On the Progressive or Populist side were those who opposed the endless wars in the Middle East, and on the Establishment side those who supported those long and bloody wars.  On the Progressive Side were those who supported badly needed domestic reforms, most notably Medicare for All, which after all is a reform of almost 20% of the entire economy and a reform that has to do with life itself. In contrast on the Establishment side were those who supported ObamaCare, a device for leaving our health care to the tender mercies of the Insurance behemoths with its ever increasing premiums and ever decreasing coverage.
In 2016 the pundits gave progressives little chance of success. Hillary Clinton was a shoo-in, we were all assured by a horde of “reliable sources.” And given the control that the Clintonites exercised over the Democratic Party apparatus, there was little prospect of a successful rebellion and every chance of having one’s career badly damaged by opposing Party elite. Summer soldiers and duplicitous candidates were not interested in challenging the Establishment.
In 2016 Bernie Sanders was the only politician who was willing to take on the Establishment. Although not technically a Democrat, he caucused with them and worked with them. And he was a lifelong, reliable and ardent advocate for Medicare for All and a consistent opponent of the endless wars. For these things he was prepared to do battle against overwhelming odds on the chance that he might prevail and because from his grass roots contacts he sensed that a rebellion was brewing.
In 2016 only one among the current crop of candidates followed Bernie, supported him and joined him on the campaign trail – Tulsi Gabbard. At the time she was a two term Congresswoman and Vice Chair of the Democratic National Committee (DNC), a career building position, from which she would have to resign in order to support one of the candidates. Moreover, reports said she bridled at the internal bias of the DNC in favor of Hillary. To express her displeasure with the DNC and to support Bernie, she had to defy the Clinton Establishment, which might even have terminated her political career. But she was a foe of the endless wars, partly based on her own experience as a National Guard member who had been deployed to Iraq in a medical unit and saw the ravages of war first hand. So she joined Bernie, introducing him at many of his rallies and strengthening his antiwar message.
Bernie and Tulsi proved themselves in the defining battle of 2016. They let us know unequivocally where they stand. And Bernie might well have won the nomination were he not cheated out of it by the Establishment which continues to control the levers of power in the Democratic Party to this day.
In 2016 these two stood in stark contrast to the other 2020 Democratic candidates. Let us take one example of these others, Elizabeth Warren, a darling of the corporate media which often refers to her as ideologically aligned to Bernie Sanders. Perhaps she is so aligned at times – at least in words; she is after all in favor of Medicare for All, although she hastens to add that she is “open to other approaches.” That qualifier is balm to the ears of the Insurance behemoths. Translation: she has already surrendered before the battle has begun.
In 2016 a critical primary for Bernie was Massachusetts where Senator Warren wields considerable influence. Clinton defeated Sanders there by a mere 1.5% whereas she had lost to Obama there by 15% in 2008. Wikipedia said of the primary:

Following the primary, Elizabeth Warren, the state’s senior US senator, was widely criticized by Sanders supporters online for her refusal to endorse him prior to the primary. Supporters of Bernie Sanders have argued that an endorsement from Warren, whose political positions were similar to that of Sanders’s, and who was a frequent critic of Hillary Clinton in the past, could have handed Massachusetts to him.

One must conclude that either Warren does not genuinely share the views of Sanders or she is loath to buck the Establishment and fight for those views. In either event she, and the others who failed to back Bernie in 2016, are not made of the stuff that can win Medicare for All, bring an end to the regime change wars and illegal sanctions of the last four or more administrations, begin serious negotiations to end the existential nuclear peril, and address the many other problems facing us and all of humanity.
So, if you are a progressive looking at the crowded Democratic field in 2020, there is no need to be perplexed. The answer to your dilemma lies right before your eyes in the record of 2016. The two who stood up then and fought for the kind of changes you desire were Bernie and Tulsi. They walked the walk when the road was not an easy one.