Is today’s GOP too white to win?

The conditions are converging for another presidential election that will sharply divide the country along racial lines, with troubling implications no matter which side prevails.

From one direction, the Republican presidential primaries have witnessed an epic failure by the GOP contenders to attract and engage minority voters. White voters, especially older ones, are routinely casting 90% or more of the votes in GOP contests this year, at least as high a proportion as in 2008.

Simultaneously, President Obama continues to struggle among white voters, especially the white working class. In 2008, he became the first presidential nominee ever to lose white voters by double digits and still win the White House. In 2012, as minorities loom larger in the vote, Obama could lose whites even more lopsidedly and still win reelection.

As these trends intensify, the election could reinforce the hardening re-racialization of American politics. Republicans today rely on a preponderantly white coalition centered on older and blue-collar voters, many of whom express great unease not only about activist government but also about the demographic changes swelling the minority population. Democrats depend on a coalition of minorities and of white voters (particularly those with college degrees) who are the most comfortable with government activism and the propulsive demographic transformation.

This year’s tumultuous Republican race has underscored the dominance of whites, especially older white voters, in the GOP. Exit polls have been conducted in 16 states that have held Republican primaries or caucuses. In all but two, whites cast at least 90% of the ballots. Whites represented only 74% of all voters in the 2008 general election.

Among those 16 states, only Michigan has seen its minority vote share increase by more than a trace. Whites are dominating the GOP electorate even in rapidly diversifying states. In Nevada, whites were just 69% of all voters in the 2008 election, but they cast 90% of the votes in last month’s Gopcaucus. Similar gaps are evident in GOP primaries.

This year’s Republican electorate shades not only white but also gray. In 12 of the 16 states where exit polls have been conducted, voters over 50 cast at least 60% of the GOP primary votes; in the other four, they represented at least 55%. Just 43% of 2008 general election voters were that old.

All of this flags challenges for the Republican Party. The problem this fall will be to attract minority (and younger) voters who are uninspired, or even alienated, by the primaries. As Mitt Romney has hurtled to the right on immigration, recent surveys have shown Obama’s support against him matching, or exceeding, the president’s 67% showing among Latinos in 2008. Latino Republicans such as Jennifer Korn, executive director of the Hispanic Leadership Network, say that if Romney wins the nomination, he will need to vastly expand his outreach “to explain his [immigration] position.” But outreach may go only so far for a candidate who touts “self-deportation” for illegal immigrants.

If the GOP allows Democrats to continue winning four-fifths of all minority voters — as Obama did in 2008 — Republicans eventually will need to attract an implausibly high percentage of whites to win presidential elections. The conundrum is that the party’s current reliance on the most conservative whites constrains its ability to embrace policies attractive to minorities.

Today, however, the GOP’S white strength can still overcome its minority weakness. Obama could win reelection with backing from only about 39% of whites if he duplicates his 2008 showing among minorities (and if their vote share rises slightly). But Democrats couldn’t muster even that much white support during the 2010 GOP congressional landslide. And Obama has no guarantee of crossing that bar this fall. In the Allstate/national Journal Heartland Monitor poll released Friday, his approval rating among whites reached just 41%.

These contrasting racial patterns signal another tough election in November. Equally important, they show how closely the ideological divisions between the parties track racial lines, with minorities more open than most whites to an activist role for Washington in promoting opportunity and providing a safety net. That divergence is a formula for social tension and polarized debate. It’s the future that appears increasingly likely as Obama marshals a coalition powered at its core by the diversity reshaping American life, and his Republican rivals compete for an electorate that remains almost entirely untouched by it.