America is changing. It is becoming more diverse, more socially tolerant. According to the U.S. Census Bureau, whites will cease to be a majority by 2041.

Aggrieved working-class whites are alarmed. Their economic condition is perilous. Their cosy comfortable worldview, inherited from their parents and grandparents, is under assault. The overwhelming national consensus of the U.S. as a predominantly Christian, patriarchal, and yes, white society, is gone.

As minorities have been embraced by the Democratic Party, this group has flocked to the Republican Party.

A massive shift in US politics began in 1964, after US President Lyndon B. Johnson signed the historic Civil Rights Act to make racist laws illegal. In 1965, he signed the Voting Rights Act that strengthened African-American voting rights.

This triggered a backlash in the Southern states, which were once part of a confederacy that had defended slavery.Whites began to abandon the Democratic Party and move to the Republican Party en masse.

At the time the Civil Rights Act was signed into law, both Democratic and Republican parties were more diverse within each party. This created an atmosphere of compromise and deal-making in the US Congress that smoothed the legislative process.

In today's polarised politics, it's hard to believe that a Republican president, Richard Nixon, created the Environmental Protection Agency, conservative icon President Ronald Reagan signed a law granting amnesty to millions of undocumented immigrants, and Democratic President Bill Clinton signed welfare reform into law.

Hot button issues like abortion, school prayer, immigration, LGBTrights and gun control polarised both parties: College-educated liberal whites, single women and ethnic minorities have gone to the Democratic Party, while business interests, religious conservatives, conservative educated whites and in particular non-college educated whites are Republican.

While this has resulted in a virtual lock for the Republicans in one of the chambers of the US Congress –the House – growing polarisation, along with demographic changes, also provide Democrats a widening edge in presidential elections. In the last six presidential elections, Democrats have won the popular vote five times. In the preceding two decades, Republicans won five out of six presidential races.

"In 1980, Ronald Reagan won 56 percent of all white voters and won election in a 44-state landslide. In 2012. . . (Republican) nominee Mitt Romney carried 59 percent of all white voters yet lost decisively," writes David Wasserman, an analyst with the Cook Political Report. "African-Americans, Latinos, Asians and other non-whites — all overwhelmingly Democratic-leaning groups — rose from 12 percent of voters in 1980 to 28 percent in 2012."

"Republicans have sharply increased their share of the white vote, but this advantage is being undermined by other demographic changes.

In 2008 and 2012 elections, Republicans performed best with white voters without college degrees. They carried that group by 14 percentage points in 2008 and a whopping 26 points in 2012.

However, the share of these older, rural voters in the pool of voters decline 3 percentage points every four years. 

"Democrats' coalition of non-white, young and well-educated voters continues to expand every election, while Republicans' coalition of white, older and less-educated voters keeps shrinking," writes Wasserman.

Republican Party elders recognise the looming threat.

Following the defeat of Republican Mitt Romney to President Barack Obama in 2012, the Republican National Committee set up an independent review panel - the Growth and Opportunity Project.

The panel made a sobering observation: "Public perception of the Party is at record low. Young voters are increasingly rolling their eyes at what the Party represents, and many minorities wrongly think that Republicans do not like them or want them in the country."

The panel conducted focus groups in Columbus, Ohio, and Des Moines, Iowa, to listen to voters who recently left the party. "Asked to describe Republicans, they said that the Party is 'scary,' 'narrow minded,' and 'out of touch' and that we were a Party of 'stuffy old men,'" the RNC report said.

The report warned: "The nation's demographic changes add to the urgency of recognising how precarious our position has become." 

Its wise recommendation: "Among the steps Republicans take in the Hispanic community and beyond we must embrace and champion comprehensive immigration reform. If we do not, our Party's appeal will continue to shrink to its core."

Yet immigration reform is taboo in the current Republican campaign. As for wooing ethnic minorities, after Donald Trump's immigrant-baiting antics, good luck with that.

The Republican Party, however, remains exceptionally strong in the US House of Representatives and at the state level.

In the House, Republicans have a hold that's been getting stronger as the electorate has gotten more polarised. Geographical distribution and partisan redistricting has helped. "For a long time, Democrats have been overrepresented in big cities, where there are minorities and liberals and college-educated people and gays, and under­represented everywhere else," political scientist Gary C. Jacobson, an expert on congressional politics, told political analyst Ronald Brownstein. 

Every 10 years, when voting districts are revised, Republicans enhance their advantage in states they control through a re-zoning tactic called gerrymandering. For instance, voters in a district with a huge Democratic advantage can be dispersed into adjacent districts with an overwhelming Republican advantage.

It is their advantage with whites, though, that ensures Republican control of the house.

"Whites exceed their share of the national population in 263 House districtsfully three-fifths of the total number of seats," Brownstein reports. "And Republicans now hold a crushing 199 of those 263 white-leaning seats, putting them on the brink of a House majority before they even begin competing for more diverse seats."

The Republican dominance in the House has been fuelled by the spectacular rise of conservative media which directly helped the rise of the Tea Party movement, a grassroots, non-college white protest against President Barack Obama's healthcare programme, and helped Republicans take control of the House in 2010.

"The challenge of spreading and germinating the Tea Party idea was surmounted with impressive ease because a major sector of the U.S. media today is openly partisan – including Fox News Channel, the right-wing 'blogosphere,' and a nationwide network of right-wing talk radio programmes," Theda Skocpol and Vanessa Williamson write in their 2012 book, The Tea Party and the Remaking of Republican Conservatism. 

The writer is an Atlanta (US) based freelance journalist.