A tea party supporter in Mississippi waves an American flag in 2014. (Edmund D. Fountain/For The Washington Post)

With election year a month away, American politics is caught up in tensions, ironies and a certain amount of sheer madness.

On the one hand: The U.S. economy is a marvel, driven forward by technological innovation, the promises of Big Data and Advanced Manufacturing, a relative independence in energy supply, and a population younger than those of most other wealthy nations.

On the other hand: Wages have been stagnating since the turn of the millennium, inequalities are widening, college is out of reach for many, suicide rates among white middle-aged working-class people are rising and, in a recent Public Religion Research Institute poll, 72 percent of Americans said “the economy is still in a recession.”

On the one hand: Republicans have lost the popular vote in five of the past six presidential elections and have, at best, a very narrow path to an Electoral College majority next year. The rising groups in the American electorate — Latinos, Asian Americans and young people — are hostile to the party, a problem its presidential front-runner is making worse with his unapologetic xenophobia.

On the other: Democrats have their fewest seats in state legislatures since the 1920s, their fewest in the House since the late 1940s, and they control only 19 governorships. In the past two midterm contests, they have suffered wipeouts.

Donald Trump met a look-a-like supporter at a rally for the Republican presidential candidate in Myrtle Beach, S.C. on Nov. 24. (Reuters)

If reality is so contradictory, we shouldn’t be surprised that different groups choose to see it differently. We are divided evenly, 49 percent to 49 percent, on the question of whether “America’s best days are ahead of us or behind us,” according to the PRRI poll. Among liberal Democrats, 67 percent think our best days are yet to come; only 40 percent of conservative Republicans share this confidence.

One of the tasks of political analysis is to make sense of conflicting information, and a new book by Stanley Greenberg, who was a political scientist before he became a Democratic pollster, does not shy away from the messiness of our social and electoral landscape. My Dickensian “best of times, worst of times” analysis is drawn partly from Greenberg’s new book, “America Ascendant.” In it Greenberg sees Republicans in a long-term demographic “death spiral.” But the book is also unsparing in acknowledging that Democratic weaknesses among older white and rural voters leave the GOP “almost unopposed in nearly half of the states.”

I should say that I have been an unabashed Greenberg fan for a quarter-century. Our political views are similar, and I especially like his resistance to gloom about America’s future. I truly believe (and maybe this just proves I’m a liberal) that only the dysfunction of our politics will keep our country from having another good century. Yes, we face real threats, including terrorism. But we are not paying enough attention to our strengths, including the advantages of a social diversity that is causing such unease among many of our fellow citizens.

The power of Greenberg’s analysis is that he doesn’t dismiss the anger of these Americans, so many of whom are rallying to Donald Trump. Written before Trump’s rise, the book doesn’t mention him, but Greenberg treats what has become the Trump constituency with a heartfelt empathy.

The sorts of voters who rally to Trump have reason to be upset, he says, because the very economic and social changes that contribute to growth also create “stark problems for people and the country that leave the public seething, frustrated, and pessimistic about the future . . . .” There are no wage gains for most, “working-class men have been left marginalized,” and the proportion of children being born to single parents has soared.

Greenberg is open to changes in our mores and insists that progressive policies on family leave, pay, taxes and prekindergarten programs are more plausible responses to these problems than sermonizing. But if his book provides Democrats with good news about their national political advantages, it pointedly challenges them to address rather than ignore or dismiss the reasons for the thunder on the right.

A dialogue I would like to see would be between Greenberg and Republican pollster Whit Ayres, who is working for Marco Rubio’s presidential campaign and whose own book, “2016 and Beyond,” is unstinting in facing up to the profound demographic problems the GOP confronts.

Republican presidential candidate Donald Trump has a heckler "nicely" escorted out of a campaign rally in Sarasota, Fla. (Reuters)

Even better, Republican presidential candidates should propose ways of easing the discontents that Trump and others in their ranks are merely exploiting. “The citizenry is ready for a cleansing era of reform that allows America to realize its promise,” Greenberg writes. It would be helpful if the campaign gave us more reason to think he’s right.

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