At the other end of the scale, in 2008 Democrats represented a majority of the 30 poorest districts, 22-8. After the 2018 election, the poorest districts were evenly split between the two parties.

Greenberg, of course, understands this perfectly well. He pointedly notes in “RIP GOP” that “Democratic leaders contributed mightily to the alienation of voters that produced successive disruptive elections that put the Republicans in power” and argues that “the Democrats will not run in 2020 calling out to every aggrieved group in its potential winning coalition, as Hillary Clinton did so disastrously in 2016.”

While well-to-do Democrats became increasingly preoccupied with moving the party in a progressive direction on social and cultural issues, many low- and moderate-income voters living in less densely settled regions of the country had different concerns.

Anusar Farooqui, a doctoral candidate in history at Columbia, writes for Policy Tensor. He argues that the inability of the Obama administration to ameliorate the devastating consequences of the 2008 economic meltdown in much of rural and small-town America contributed to the 2016 swing to Trump in working- and middle-class districts that had voted for Obama:

The strong correlations between education, population decline, and deaths of despair on the one hand, and the electoral swing to Trump on the other, is clear. There has been a breakdown in elite-mass relations. Vast portions of the country are in serious trouble. A lot of faith was invested in Obama in 2008 in the shadow of the financial crises. That faith was already shattered in 2012, despite the false dawn of Obama’s victory.

Trump, Farooqui continues, “was no surprise. An enterprising political analyst could have looked at the pattern already evident in 2012 and predicted further instability.”

Isabel Sawhill, a senior fellow at Brookings, has been thinking along similar lines. She wrote me:

Democrats did not do enough when they were in power to tackle the rise in inequality, inadequate education and health care, stagnant wages, and declining communities that would, in time, create a frustrated electorate — all too ready to elect a Donald Trump in 2016.

Sawhill focuses on economic liberalism with little or no reference to the social and cultural issues that have often proven most problematic for Democrats.

“My conclusion,” Sawhill wrote:

Democrats must first win the White House and the Congress and then begin to address the deep-seated problems that have been neglected for far too long. Trump’s current problems make that possible, just as Watergate made Carter’s election possible, but it would be a mistake to move too far left and lose the chance to begin the reform process.

If they are victorious, will Democrats overreach on either the nexus of social and cultural issues or on economic issues? Will they raise taxes on the middle classes to pay the costs, say, of Medicare for all? Or will they take Sawhill’s advice and focus on more easily achievable progressive economic policy aimed at building financial security and an improved standard of living for those in the bottom four fifths of the income distribution?

There are no obvious answers here, despite the flame throwing on both sides of the left-vs.-left-of-center debate. There is a credible argument, as Ryan Enos, a professor of government at Harvard contends, that the public is prepared to support a turn to the left:

The question is whether the mass public had already begin moving to the left before Trump and I think there is reason to believe this is the case.

Trump “may be the last gasp of a dying policy regime of Reagan conservatism that started to end with the election of Obama,” according to Enos. If that’s true,

then Democrats will have much more freedom to enact liberal policy reform because the policy mood of the median voter has already moved left and would have done so even without the extra push provided by Trump.

Along similar lines, Gary Jacobson, professor emeritus of political science at the University of California-San Diego, wrote in reply to my inquiry:

The Republican coalition is on the defensive, threatened by demographic changes, and the overall trend of public opinion is in a more liberal direction, certainly on social issues but probably on environmental and economic issues as well.

Jacobson sees little or no prospect for a renewal of

a strong rightward shift in aggregate opinions on national issues more generally. Support for gay marriage, etc., is here to stay, and demands for action on climate change will only grow because the consequences of inaction are becoming increasingly obvious and prospectively dire.

Let’s shift from academics back to political practitioners for a moment. Paul Begala, a Democratic strategist, succinctly described the danger of Democratic overreach: “I am deeply concerned about Democratic presidential candidates getting too far over their ski tips.”