For all the energy around lefty ideas like a Green New Deal and Medicare-for-all, there is still a great deal of moderation left in the Democratic Party. Centrists may not have much in the way of fresh ideas — even Joe Biden is running well to the left of the Clinton 2016 campaign — but they still comprise much of the party's congressional caucus and intellectual class.

A lefty like Bernie Sanders or Elizabeth Warren may well win the presidency in 2020. But this moderate tendency will remain a tremendous obstacle to both repairing what is broken in America and confronting the corruption and extremism of the Republican Party.

The problems with moderate Democrats can be divided into two categories: temperament and policy. On the former, many moderates have a bizarre reticence to matching up their political tactics with the dire reality of our current political moment. When Washington Nationals fans booed President Trump at Game 5 of the World Series recently, and some chanted "lock him up!" — both an ironic troll of one of Trump's signature chants, and a reference to his gargantuan, ongoing crime spree — some high-profile moderates were outraged. "Frankly think the office of the president deserves respect," tut-tutted Senator Chris Coons (D-Del.), who is also a surrogate for Joe Biden.

It's of a piece with the months-long reluctance to start up an impeachment inquiry and foot-dragging on getting Trump's tax returns. Luckily that inquiry is finally underway (thanks mostly to Trump himself), but Rep. Van Drew (D-N.J.) already said he won't vote for Thursday's resolution making it official.

It is a bit mysterious why moderates as such should behave in this fashion. Ostensibly moderation is all about pragmatism and caution — at least according to their own lights, they prefer the easier, workable solution that puts less at risk than a more radical, utopian plan that might backfire. But what is pragmatic and cautious depends entirely on context. When faced with a severe crisis — say a hideously corrupt president who is openly contemptuous for constitutional government — stuffily insisting on Civil Rhetoric from the opposition is idiotic. As David J. Roth writes at Deadspin, "They respect the office of the presidency so much that they insist on treating it with a reverence that Donald Trump, as its occupant, plainly cannot merit."

If moderate Democrats actually believed their own rhetoric, they would calibrate their politics, and realize the obvious fact that Trump deserves furious, no-holds-barred opposition. But they don't. Moderation in practice is an incoherent mish-mash of professional-class office decorum, mere timidity, and learned helplessness — backed up by a political model which relies heavily on big-dollar donors who do not want a politically mobilized population, lest they start demanding expensive new benefit programs or regulations. To adjust Upton Sinclair, it's hard to get a member of Congress to understand something when his next campaign fundraiser depends on him not understanding it.

This problem very much carries over into the policy realm. Moderate Democratic presidential candidates and members of Congress are against sweeping reforms like Medicare-for-all or free college not because they are actually impractical but because they are big, and that is wrong by definition. Backers of health care half-measures like Pete Buttigieg do not seriously reckon with how severe the breakdown in the employer-sponsored insurance system is, nor that their plans could cost more than Medicare-for-all when all spending is considered.

Indeed, free college would be relatively cheap. Contrary to Amy Klobuchar's sneering — "If I was a magic genie and could give that to everyone and we could afford it, I would" — just the 2018 increase in the military budget (that Klobuchar voted for, naturally) would be enough to pay for all public college tuition across the entire country.

Or take climate change, where only Bernie Sanders is the only 2020 candidate proposing anything like a solution on the scale of the problem:

And yet, moderates like Joe Manchin (D-W.V.) and Krysten Sinema (D-Ariz.) are probably going to be the swing votes for any kind of legislation. Manchin, a coal baron whose daughter is a ruthless pharmaceutical executive, will certainly not vote for a Green New Deal and probably even not for a public option. Meanwhile, Sinema will not even promise to vote for the Democratic nominee in 2020, despite the fact that, as Eric Levitz writes at New York, Arizona is about as swingy as Wisconsin, trending blue fast, and she is not up for reelection until 2024. Elsewhere, former Colorado Governor John Hickenlooper, who is not as wretched as Sinema but still well to the right of his state's center of political gravity, is running for Senate.

It is hard to know what to do about these moderates, in part because the situation is objectively very difficult. Primaries are hard to run and win, and senators are only up for reelection every six years. Aside from that, Sanders has one of only a few ideas I've seen that could even theoretically work — namely, activating an enormous chunk of the nonvoting population that will apply popular pressure on these moderates, and hence change the political calculation. In an interview with CNBC's John Harwood, he said that people like Manchin would have no choice but to support the Sanders agenda: "Damn right they will. You know why? We're going to go to West Virginia."

Manchin, for his part, responds that "Bernie is damn wrong on that one." And he might well be. But if he is, the consequences could be gruesome indeed. A recent study tripled the number of people who would be flooded by 2050 by climate change-induced sea level rise, to 150 million. In an age of murderous oligarchs and accelerating climate disasters, alternately sitting on our hands, fussing about impolite protests, and passing the occasional fiddly tax credit is going to kill millions.

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