Given the kind of things the Republican presidential candidates have been saying every day for weeks now, you might reasonably conclude that US politics is stuck not just in another decade, but in a previous century. Ben Carson thinks Obamacare is “the worst thing that has happened in this nation since slavery”. To boost an argument against gun control Carson also said that Hitler would have killed fewer Jews in the Holocaust “if the people had been armed”. Donald Trump, meanwhile, would expel 12 million undocumented migrants because so many are “criminals, murderers and rapists”. Carly Fiorina asserts that “every single policy” Hillary Clinton espouses, including paid family leave and equal pay for women, “has been demonstrably bad for women”.

Ben Carson claims Jewish people might have stopped Holocaust if they had guns Read more

This Republican race to the political bottom is happening because America’s conservatives are losing the culture wars. The US is now beyond the electoral tipping point, driven by a new progressive majority in the electorate: racial minorities (black and Hispanic) plus single women, millennials (born between 1982 and 2000) and secular voters together formed 51% of the electorate in 2012; and will reach a politically critical 63% next year.

And each of these groups is giving Clinton, or whoever emerges as the Democratic candidate for the 2016 White House race, at least a two-to-one advantage over a Republican party whose brand has been badly tarnished.

The country today, particularly the bigger urban centres, is being dramatically remade by the hi-tech, internet, big data and energy revolutions. Just as important are the revolutions in migration, the family, gender roles and religion. Together these revolutions are producing seismic and accelerating changes to the economy, culture and politics – which is what animates so many Republican candidates. America is emerging as racially blended, immigrant, multinational, multicultural and multilingual – a diversity that is ever more central to its political identity. We are not talking here about trends, but profound demographic changes accompanied by a dramatic shift in values. They have produced a country where racial minorities form 38% of the population, and 15% of new marriages are interracial. One in five global migrants end up in the US, and thus nearly 40% of the populations of New York and Los Angeles are foreign born, as are 50% of Silicon Valley’s engineers and more than half of US Nobel laureates.

Facebook Twitter Pinterest Karl Rove, George W Bush and first dog Barney. ‘Rove saw moral issues such as opposition to gay marriage as the most powerful force in politics.’ Photograph: Dennis Brack/EPA/Corbis

Since 2011 a majority of Americans have been living in unmarried households, and a diversity of family types – from same-sex marriages and cohabitation to remarriage after divorce, delayed child-rearing, childlessness and those who never marry – is now accepted. Millennials are in fact marrying later and having few children, while working class women are avoiding marriage with working class men who are no longer assured of secure, decent-paying manufacturing jobs. With the traditional male breadwinner role nearly extinct, three-quarters of women are now in the labour force and two-thirds are the principal or joint breadwinner. The result: single women will form a quarter of the electorate in 2016. Religious observance meanwhile has plummeted across all religious denominations, with the exception of white evangelicals. People who define themselves as secular now outnumber mainline Protestants.

The political landscape is also being reshaped by a reversal of the historic pattern of mobility and home ownership. The middle class ladder used to take every generation and new wave of immigrants from city centres to suburbs to the exurbs. But in the past decade cities, with their falling crime rates, have attracted more people – particularly retiring baby boomers – than suburbs, and real estate values in metropolitan areas have risen faster than elsewhere and created more jobs. At the same time, only half of millennials have a driver’s licence, a rite of passage for prior generations.

Nick-naming women 'Beyoncé voters' is exactly why we don't vote Republican | Jessica Valenti Read more

Not only are baby boomers now outnumbered by millennials – but also the groups could not be more different: 66% of boomers are married, 72% are white and their income is $13,904 above the national median; over 40% of millennials are racial minorities, 60% are single and three-quarters believe America’s diversity of race, ethnicity and language makes the country stronger.

All this social disruption has taken place at remarkable speed: the political centre of gravity has in effect swung from right to centre in under a decade. When Barack Obama first ran for the White House in 2008, 46% of Americans described themselves as conservative, but that has fallen to 37% now. In some national polls, the number of American liberals equals the number of conservatives. Gallup marked 2015 as the year when cultural attitudes reached a significant benchmark: when 60-70% of the country said gay and lesbian relations, having a baby outside marriage or sex between unmarried women and men were all “morally acceptable”.

The shift marked by these polls reflects the new American majority and explains why next year’s election will prove shattering and divisive for the Republican party, even if it retains its strongholds in the House of Representatives and states.

It also explains why, since 2004, Republicans have been engaged in a ferocious counter-revolution to stop these new and expanding demographic groups from coalescing to form a politically coherent bloc capable of governing successfully. The tactic adopted by Karl Rove, George W Bush’s election strategist, and other social conservatives was to forsake “big tent Republicanism” and the swing voter. Instead of an earlier emphasis on “compassion” or the “Latino vote”, they made politics a battle for social and cultural values – “American values” – that would raise the stakes and engage those who leaned furthest to the right, particularly evangelicals and the religiously observant. Rove’s ambition was to create a permanent Republican majority, and he saw “moral” issues such as opposition to gay marriage as the most powerful force in politics. Indeed, he used them to galvanise enough support to get Bush re-elected in November 2004.

But the culture war ignited by Rove is a fire that requires ever more toxic fuel – it only works by raising fears of the moral and social Armageddon that would follow a Democratic victory.

The Republicans have, of course, won big numbers of seats at state level and in off-year elections in the past decade. However, their conservative supporters, motivated by moral purpose, are now angry that Republican leaders have failed to stop Obama, particularly as the country, as they see it, tips into global and economic oblivion.

On the other hand, this intensifying battle for values has also left the Republicans with the oldest, most rural, most religiously observant, and most likely to be married white voters in the country. These trends have pushed states with large, growing metropolitan centres, such as Florida, Virginia and Colorado, over the blue Democratic wall, creating formidable odds against Republicans winning the electoral college majority needed to win the presidency.

Encamped in the 20 states of the south, the Appalachian valley, parts of the plains states and Mountain West, conservatives have waged their culture wars to great effect. But those states account for only 25% of the voters. Success here turns Donald Trump, Ben Carson and Ted Cruz into plausible candidates – but not plausible presidents in a country that is past the new electoral tipping point. America will get to send that message 12 months from now.

• Stanley Greenberg is the author of America Ascendant: A Revolutionary Nation’s Path to Addressing Its Deepest Problems and Leading the 21st Century

• This article was amended on 12 November 2015. An earlier version referred to the right, rather a rite, of passage.

