For decades, Democrats have suffered continuous and increasingly severe losses among white voters. But preparations by Democratic operatives for the 2012 election make it clear for the first time that the party will explicitly abandon the white working class.

All pretence of trying to win a majority of the white working class has been effectively jettisoned in favor of cementing a center-left coalition made up, on the one hand, of voters who have gotten ahead on the basis of educational attainment — professors, artists, designers, editors, human resources managers, lawyers, librarians, social workers, teachers and therapists — and a second, substantial constituency of lower-income voters who are disproportionately African-American and Hispanic.

It is instructive to trace the evolution of a political strategy based on securing this coalition in the writings and comments, over time, of such Democratic analysts as Stanley Greenberg and Ruy Teixeira. Both men were initially determined to win back the white working-class majority, but both currently advocate a revised Democratic alliance in which whites without college degrees are effectively replaced by well-educated socially liberal whites in alliance with the growing ranks of less affluent minority voters, especially Hispanics.

The 2012 approach treats white voters without college degrees as an unattainable cohort. The Democratic goal with these voters is to keep Republican winning margins to manageable levels, in the 12 to 15 percent range, as opposed to the 30-point margin of 2010 — a level at which even solid wins among minorities and other constituencies are not enough to produce Democratic victories.

“It’s certainly true that if you compare how things were in the early ’90s to the way they are now, there has been a significant shift in the role of the working class. You see it across all advanced industrial countries,” Teixeira, a senior fellow at the Center for American Progress, said in an interview.

In the United States, Teixeira noted, “the Republican Party has become the party of the white working class,” while in Europe, many working-class voters who had been the core of Social Democratic parties have moved over to far right parties, especially those with anti-immigration platforms.

Teixeira, writing with John Halpin, argues in “The Path to 270: Demographics versus Economics in the 2012 Presidential Election,” that in order to be re-elected, President Obama must keep his losses among white college graduates to the 4-point margin of 2008 (47-51). Why? Otherwise he will not be able to survive a repetition of 2010, when white working-class voters supported Republican House candidates by a record-setting margin of 63-33.

Obama’s alternative path to victory, according to Teixeira and Halpin, would be to keep his losses among all white voters at the same level John Kerry did in 2004, when he lost them by 17 points, 58-41. This would be a step backwards for Obama, who lost among all whites in 2008 by only 12 points (55-43). Obama can afford to drop to Kerry’s white margins because, between 2008 and 2012, the pro-Democratic minority share of the electorate is expected to grow by two percentage points and the white share to decline by the same amount, reflecting the changing composition of the national electorate.

The following passage from “The Path to 270” illustrates the degree to which whites without college degrees are currently cast as irrevocably lost to the Republican Party. “Heading into 2012,” Teixeira and Halpin write, one of the primary strategic questions will be:

Will the president hold sufficient support among communities of color, educated whites, Millennials, single women, and seculars and avoid a catastrophic meltdown among white working-class voters?

For his part, Greenberg, a Democratic pollster and strategist and a key adviser to Bill Clinton’s 1992 campaign, wrote a memorandum earlier this month, together with James Carville, that makes no mention of the white working class. “Seizing the New Progressive Common Ground” describes instead a “new progressive coalition” made up of “young people, Hispanics, unmarried women, and affluent suburbanites.”

In an interview, Greenberg, speaking of white working class voters, said that in the period from the mid-1960s to the early 1990s, “we battled to get them back. They were sizeable in number and central to the base of the Democratic Party.” At the time, he added, “we didn’t know that we would never get them back, that they were alienated and dislodged.”

In his work exploring how to build a viable progressive coalition, Greenberg noted, he has become “much more interested in the affluent suburban voters than the former Reagan Democrats.” At the same time, however, he argues that Republican winning margins among white working-class voters are highly volatile and that Democrats have to push hard to minimize losses, which will not be easy. “Right now,” he cautioned, “I don’t see any signs they are moveable.”

Teixeira’s current analysis stands in sharp contrast to an article that he wrote with Joel Rogers, which appeared in the American Prospect in 1995. In “Who Deserted the Democrats in 1994?,” Teixeira and Rogers warned that between 1992 and 1994 support for Democratic House candidates had fallen by 20 points, from 57 to 37 percent among high-school-educated white men; by 15 points among white men with some college; and by 10 points among white women in both categories. A failure to reverse those numbers, Teixeira warned, would “doom Clinton’s re-election bid” in 1996.

Teixeira was by no means alone in his 1995 assessment; he was in agreement with orthodox Democratic thinking of the time. In a 1995 memo to President Clinton, Greenberg wrote that whites without college degrees were “the principal obstacle” to Clinton’s re-election and that they needed to be brought back into the fold.

In practice, or perhaps out of necessity, the Democratic Party in 2006 and 2008 chose the upscale white-downscale minority approach that proved highly successful twice, but failed miserably in 2010, and appears to have a 50-50 chance in 2012.

The outline of this strategy for 2012 was captured by Times reporters Jackie Calmes and Mark Landler a few months ago in an article tellingly titled, “Obama Charts a New Route to Re-election.” Calmes and Landler describe how Obama’s re-election campaign plans to deal with the decline in white working class support in Rust Belt states by concentrating on states with high percentages of college educated voters, including Colorado, Virginia and New Hampshire.

There are plenty of critics of the tactical idea of dispensing with low-income whites, both among elected officials and party strategists. But Cliff Zukin, a professor of political science at Rutgers, puts the situation plainly. “My sense is that if the Democrats stopped fishing there, it is because there are no fish.”

As a practical matter, the Obama campaign and, for the present, the Democratic Party, have laid to rest all consideration of reviving the coalition nurtured and cultivated by Franklin D. Roosevelt. The New Deal Coalition — which included unions, city machines, blue-collar workers, farmers, blacks, people on relief, and generally non-affluent progressive intellectuals — had the advantage of economic coherence. It received support across the board from voters of all races and religions in the bottom half of the income distribution, the very coherence the current Democratic coalition lacks.

A top priority of the less affluent wing of today’s left alliance is the strengthening of the safety net, including health care, food stamps, infant nutrition and unemployment compensation. These voters generally take the brunt of recessions and are most in need of government assistance to survive. According to recent data from the Department of Agriculture, 45.8 million people, nearly 15 percent of the population, depend on the Supplemental Nutrition Assistance Program to meet their needs for food.

The better-off wing, in contrast, puts at the top of its political agenda a cluster of rights related to self-expression, the environment, demilitarization, and, importantly, freedom from repressive norms — governing both sexual behavior and women’s role in society — that are promoted by the conservative movement.

While demographic trends suggest the continued growth of pro-Democratic constituencies and the continued decline of core Republican voters, particularly married white Christians, there is no guarantee that demography is destiny.

The political repercussions of gathering minority strength remain unknown. Calculations based on exit poll and Census data suggest that the Democratic Party will become “majority minority” shortly after 2020.

One outcome could be a stronger party of the left in national and local elections. An alternate outcome could be exacerbated intra-party conflict between whites, blacks and Hispanics — populations frequently marked by diverging material interests. Black versus brown struggles are already emerging in contests over the distribution of political power, especially during a current redistricting of city council, state legislative and congressional seats in cities like Los Angeles and Chicago.

Republican Party operatives are acutely sensitive to such tensions, hoping for opportunities to fracture the Democratic coalition, virtually assuring that neither party can safely rely on a secure path to victory over time.