Mr Donald Trump's acceptance of the Republican nomination last Thursday in Cleveland represented a stunning moment in American politics - the triumph of a raw populism, embodied by a shameless demagogue, over both the official establishment and the official ideology of a major political party.
We did not see Mr Trump's apotheosis coming. But in our 2008 book, Grand New Party, we pointed out that despite its "party of the rich" reputation, the Republican Party increasingly depended on mostly white working-class support, even as its policy agenda was increasingly unresponsive to working-class voters' problems and concerns.
Now Mr Trump has brought this tension fully into the open and ruthlessly exploited it.
His primary-season base was more working class and less religious and libertarian than is usual for Republican nominees, and his campaign trafficked in overtly populist rather than ideologically conservative appeals: protectionist talk on trade and immigration, an "America First" foreign policy vision, a promise to protect Social Security and Medicare, and an unsubtle emphasis on white identity and white nostalgia.
Of course Trumpism is also a celebrity-driven cult of personality, forged by its leader's unique reality-television appeal. This has made it relatively easy for the Republican Party's leaders to hope that his campaign is sui generis, that when he loses in November, as most of them still expect, there will not be a coherent Trumpism after Mr Trump.
If Mr Trump's working-class supporters were voting as much for the man as for his message, they were also clearly voting against a party leadership that pays them lip service while ignoring their concerns. Some of these concerns are rooted in racial anxiety, and an older generation's inevitable fear of change.
In the short term, they might be right: In 2018 and 2020, Republican politics might return to an uneasy normalcy. But if Mr Trump's working-class supporters were voting as much for the man as for his message, they were also clearly voting against a party leadership that pays them lip service while ignoring their concerns.
Some of these concerns are rooted in racial anxiety, and an older generation's inevitable fear of change. But many of them are rooted in basic human vulnerability - a very personal exposure to stagnant wages, family breakdown, military quagmires (America's wars are disproportionately fought by volunteers from downscale Red America) and a social crisis of opioid abuse and suicide that hardly anyone in Washington or New York noticed until recently.
These are problems that deserve a political response no matter what racial biases the people experiencing them may harbour.
Keep stringing these voters along with symbolism, and they will eventually seek another Mr Trump.
DEFINE THE NATIONAL INTEREST
So what should the Republican Party offer them instead?
The best answer is conservative politics that stress the national interest abroad and national solidarity at home. It should define America's overseas goals in more achievable terms than the Bush-era "freedom agenda" or a Hillary Clinton-in-Libya liberal interventionism; promise support to workers buffeted by globalisation; and explicitly weigh questions of community and solidarity when it sets tax rates or immigration levels.
Begin with foreign policy, where one of Mr Trump's more grotesque innovations has been his praise of Russian leader Vladimir Putin, and his nostalgia for Muammar Gaddafi and Saddam Hussein.
But Mr Trump has put his finger on a real problem: The Republican Party since the Sept 11 attacks has struggled to weigh the relative gravity of different threats, to devise a strategy that distinguishes between bad and worse (as our Cold War strategy generally did), to offer a vision that does not seem to promise escalation on every front simultaneously.
To voters who watched their children bleed in Iraq and Afghanistan, or who have bled themselves, the party has not provided much reassurance that it has learnt lessons from those conflicts.
The consensus critique of President Barack Obama from not-Trump Republicans often seemed to be that he should have kept more troops in Iraq and Afghanistan, sent more troops to Libya, intervened in Syria, sent more arms to Ukraine, expanded Nato's presence in the Baltics, and been more willing to bomb Iran and so on. Some of these policy prescriptions are reasonable, but taken together, they look like a road map for more quagmires, more Afghanistans and Iraqs. This is the landscape in which Mr Trump's "America First" language resonated.
And the ease with which Mr Trump crushed Mr Jeb Bush, in particular, suggests that it will continue to resonate until Republican leaders become more selective in their hawkishness, more comfortable with five simple words: Invading Iraq was a mistake.
The same need to define the national interest applies to the immigration debate, where the leaders of both parties seem viscerally uncomfortable with the idea that the United States should strongly favour high-skilled immigrants over low-skilled immigrants.
Among libertarian-minded conservatives as well as liberals, it is an article of faith that scepticism about mass immigration is driven largely by racism, and Mr Trump's campaign has powerfully reinforced this assumption.
But when you dig into survey data, immigration scepticism seems to be rooted as much in concerns about how quickly immigrants assimilate, whether they rely on welfare programmes and whether they compete for American jobs, as it is in racial or cultural anxiety.
Such concerns are reasonable.
While less-educated immigrants are no less admirable and hard-working than those who have managed to acquire the skills most prized in our polarised labour market, there is clear evidence that they and their children need more of a helping hand from social programmes, and that their descendants are more likely to assimilate downwards when that help does not suffice.
The US is already unique among the world's affluent market democracies in our level of entrenched poverty.
Since the New Deal era, we have created a thicket of programmes for the poor that are notorious for their complexity, their expense and sometimes their inadequacy.
Both liberals and conservatives have recognised that our tools for fighting poverty are failing the poorest of the poor, and that our society could face a growing scourge of worklessness.
Given these problems, an immigration policy in the national interest should explicitly try to attract immigrants who will be in a strong position to provide for their families in a difficult economic environment. It should encourage a market in which employers have to compete more for less-skilled labour, to slow the alarming retreat from paying work among native-born working-class men.
This does not require closing the door to legal status for the millions of illegal immigrants already here.
But it requires a very different policy approach. Instead of "Gang of Eight"-style bills that hide instant legalisation and higher levels of low-skilled immigration under a fig leaf of border toughness, Republicans should make any path to permanent legal status conditional on steady year-over-year cuts in the pace of low-skilled immigration, both legal and illegal.
REPAIR BREACH OF TRUST
This brings us to larger questions of domestic policy, where Mr Trump has brought to the surface deep divisions between the party elite and its working-class voters on taxes and spending.
There have always been rank-and-file Republicans who favour higher taxes on the rich, and though Mr Trump's official tax plan cuts them drastically, he has shrewdly made populist noises about forcing Wall Street tycoons to pay their fair share.
Nothing unites elite conservatives more than their support for bringing entitlement spending under control. But by frequently insisting that he would never cut Social Security and Medicare benefits, and basically endorsing universal healthcare, Mr Trump has put himself on the side of millions of grassroots Republicans.
If Republicans are to address the anxieties of Mr Trump's voters, they should be looking for ways to bridge these divides. On taxes, for example, the party would do well to focus on measures that raise working Americans' take-home pay - not down the road, but right now, in a clear and quantifiable way.
There are various ways to accomplish this, such as payroll tax cuts, family-friendly tax reform, wage subsidies or a larger earned-income tax credit. Republicans like Mr Marco Rubio of Florida, Mr Mike Lee of Utah and Mr Paul Ryan have championed some of these ideas. But they have often played second fiddle to big upper-bracket tax cuts.
So Republicans trying to demonstrate that they have learned something from the Trump trauma should consider embracing a new tax pledge. The party will still back tax cuts for the middle class and revenue-neutral tax reforms. But there should be no new income tax cuts for households earning US$250,000 (S$340,000) or more.
This self-denying ordinance will be difficult for supply-siders to bear, and it will have certain economic downsides. Under the right circumstances, tax cuts for the rich really do have virtues. For now, however, Republicans need to repair a breach of trust.
Similarly, Republicans need to rethink how they talk about health care and retirement. The party has already moved away, wisely, from its Bush-era attempt at Social Security privatisation, and figures like Mr Ryan are always careful to stress that they are protecting entitlements for the long term, not just arbitrarily cutting them.
But more can be done to reassure the voters who depend on Medicare and Social Security - and now Medicaid and ObamaCare - that their interests will be protected when the programmes are reformed.
This might mean instituting a minimum Social Security benefit while curbing benefits for high earners, or using competition to curb cost growth in Medicare and Medicaid while also expanding coverage to include long-term care.
It means recognising that ObamaCare's coverage expansion is here to stay, and reassuring voters that any reform of healthcare reform will maintain the coverage of working-class Americans who were previously slipping through cracks.
Politics that stress national solidarity is not just the best way to keep Trump voters from tearing down the party's tent. It is also the most plausible path up from white-identity politics to a one-nation, pan-ethnic conservatism.
A more nationalist politics is, in one sense, a more exclusive politics, as it is based on the premise that there is such a thing as an American national community, and that this community's interests at times must be placed ahead of humanity as a whole.
But nationalism can also be inclusive, insofar as it emphasises the interests that Americans of all classes and ethnic backgrounds share.
Why should privileged Americans care more about the fate of children raised in low-income US households than poorer children elsewhere in the world? Part of the reason is that all Americans live under the same government, and if its policies fail the most vulnerable among us, its very legitimacy is in question. Another part, however, is that as Americans, we are - or ought to be - linked by bonds of affection and a sense of shared fate.
If the Republican Party wants to offer this kind of unifying nationalism, it clearly needs to abandon Mr Trump's explicit appeals to white identity. But that is just a baby step.
The only way that Republicans can actually win more Hispanics or African-Americans is by expanding their party's vision of the American nation to fully include those voters and by persuading them that the party cares about their fate.
In part, that is the work of public rhetoric. No laundry list of policy proposals can substitute for an eloquent narrative of inclusion.
But policy has its place in any political vision, as Mr Trump's various heresies have proved.
Even the most inclusive rhetoric will always ring hollow unless the party can address the economic anxieties and doubts about its foreign-policy competence that both minority voters and Mr Trump's voters tend to share.
Some liberals believe that this kind of shift is basically impossible - that racism and right-wing politics are so deeply intertwined that any Republican populism will just end up defending welfare for white people, that any "immigration in the national interest" proposals will descend into "Mexican rapists" one-liners on the campaign trail.
Sadly, Mr Trump has offered powerful evidence for the liberals' perspective. But if the Republican Party hopes to recover from his destructive rise, it has no alternative except to try to prove them wrong.
NEW YORK TIMES
- Ross Douthat, a columnist for The New York Times, and Reihan Salam, the executive editor of National Review and a columnist at Slate, are the authors of Grand New Party: How Republicans Can Win The Working Class And Save the American Dream.