Democrats who think that the appropriate answer to Trump and hyper-polarization is a transcendent, "unifying" centrist candidate should be paying attention to what's happening in France.
The world heaved a sigh of relief that France avoided path traveled by other western countries by rejecting Le Pen (which was objectively good). But he won with less than a quarter of the vote and now 80% of the country rejects him. Now he's facing a full-fledged populist revolt.
Populism is a rejection of political and economic inequality, and in France's case, austerity. You can't just maneuver your way around it. Either you grapple with the conditions that engender it, or you face the social turmoil that results from ignoring it.
"Grappling with the conditions that engender it" means engaging in political conflict with the interests that benefit from inequality. It cannot mean bringing everyone together into a working consensus. If that were possible, there would be no populist threat in the first place.
IMO if Dems choose an American Macron in 2020, either s/he will lose to Trump, or will eke out a win and face a revolt similar to the Yellow Vests or Italy's Five Star Mvmt. A revolt that's broad, angry, and anti-partisan. And s/he will be congenitally unprepared to deal with it.
