Town residents listen as Democratic congressional leaders unveil their “A Better Deal” for working Americans in Berryville, Va., on July 24. (James Lawler Duggan/Reuters)

As I was running out of space in my column last Sunday, I suggested without elaboration that the Democrats need an “honest, hopeful” approach to future campaigns. Some readers — quite reasonably — found that glib. But I’m the wrong person to sketch a platform for Democrats, because, as an independent, I’m not one. (Admittedly, that hasn’t stopped Bernie Sanders.)

Will Marshall is a Democrat, well known to insiders for his long, sometimes lonely, battle to save his party from its suicidal left wing. In the 1980s, he joined Al From, Bruce Reed and others in an effort to drag the party toward the center after three epic defeats: Ronald Reagan and George H.W. Bush won the electoral college by a combined 1,440 to 174.

Their New Democrat movement found its face in Bill Clinton, whose upbeat centrism made him the first member of his party to win multiple terms since Franklin D. Roosevelt. Barack Obama went to school on Clinton’s rhetoric of optimistic pragmatism.

But memory can be short. The familiar pull from the left, personified by Sanders and his socialist surge, has steered Democrats back into the ditch. Since 2009, when Obama took office amid trumpet blasts of progressive glory, the party has lost the White House, Congress and more than 900 seats in state legislatures.

On Wednesday, Marshall launched his latest rescue project, called New Democracy and aimed at making the party competitive again in the vast countryside between the coasts. Founding members include Colorado Gov. John Hickenlooper and former senator Mary Landrieu (La.), along with mayors of such cities as Tucson, Denver, Houston and Pittsburgh.

(Gillian Brockell,Kate Woodsome,Karen Attiah/The Washington Post)

Recognizing the deep dysfunction in Washington, Marshall aims to build from the grass roots on a foundation of practical problem-solving rather than cultural division. And he seeks to plant his party on choice political turf abandoned by extremes in both parties: the high ground of optimism.

It’s shocking, really, how darkly pessimistic our politics have become. From the president’s “American carnage” inaugural address to the apocalyptic fevers of the alt-right, the Republican Party is captive to the sort of rhetoric that drives people to fill bunkers with freeze-dried goulash and homemade bullets. The Democrats, meanwhile, are in thrall to a fashionable gloom in which America’s past is only a litany of sins, its present a horror of injustices and its future an uninhabitable hothouse.

“The deep pessimism that hangs like a pall over America is an anomaly,” Marshall reminded me when we spoke about his endeavor. “It’s not the norm.”

There’s no denying that the United States faces challenges, many of them as new and perplexing as the technology that drives them. How do we create broad prosperity in an economy that demands, and enables, relentless efficiency and cost-cutting? How do we meet the needs of longer lifespans in a time of shrinking birthrates? How do we create community and shared values when communication is radically personalized and targeted? These questions, and others like them, are vast and urgent — but are best answered incrementally and experimentally.

But the United States has always faced problems, and the good news is we still have a knack for meeting them. I’ll give you an example. On the left we’re told that only fundamental changes to our lifestyles and economy can prevent an environmental disaster. From the right we hear that cutting greenhouse gas emissions will impose ruinous costs. Neither is necessarily true.

A huge share of greenhouse gas emissions — some 40 percent in the United States — come from buildings: our homes, offices, factories and so on. As recently as 2005, government scientists projected that emissions from this sector would rise more than 50 percent by 2016. Instead, building-sector emissions were 16 percent lower last year than in 2005, even though new construction had added more than 30 billion square feet. These amazing efficiency gains are saving U.S. homeowners and businesses hundreds of billions in lower energy bills.

According to the Climate Trust, America’s state and local governments, along with its world-beating private sector, can meet the goals of the Paris climate accord regardless of what happens in Washington. Indeed, they may well find their progress accelerating. These are the forces, after all, that have brought us energy independence, a widespread drop in crime rates and sharply falling water consumption, to pick just three thorny problems for which Americans are finding solutions.

Marshall is correct when he says, “There is a huge vacuum for Democrats to reclaim a language of hope and progress.” And Republicans might want to move in the same direction. The Americans I meet are tired of whining and blame games — and itching to tackle the future.

Read more from David Von Drehle’s archive.