By David Lauter, Tribune Washington Bureau

WASHINGTON — New data from Gallup starkly illustrates how a racially tinged generation gap has shaped American politics in the Obama era — a reality that likely will hurt Democrats this year, even as it threatens to damage Republican prospects for the future.

Americans 65 and older have become increasingly Republican since Obama’s election and currently stand as the only generation in which more people lean to the GOP than to the Democrats, according to Gallup’s analysis of a year’s worth of data, representing 18,000 interviews.

By contrast, the youngest voters, those aged 18-29, lean much more to the Democrats than did previous generations. Americans younger than 30 split their preference between the two parties almost evenly in 2003, but now show an 18-point preference for the Democrats, 53 percent-35 percent.

This year, that gap probably favors the GOP because older Americans are typically much more likely to turn out to vote during midterm elections than are those under 30.

In the longer term, the shift underscores the problem Republicans face in reaching voters outside their core audience of older, white conservatives.

The Gallup data indicate how much the divergence between the older and younger generations is affected by race.

The current generation of senior citizens, those aged 65-99, has grown steadily more Republican in the past three decades. In 1993, the same generation, then aged 45-79, leaned Democratic by 12 points, Gallup polling showed. By 2003, the GOP had drawn almost to parity among that group. Today, they give the GOP a 3-point edge, 48 percent-45 percent.

That shift partially coincides with another trend Gallup has documented — the significant move of white voters toward the GOP during the Obama years. During Bill Clinton’s second term, whites leaned toward the GOP, but by only slightly more than 4 percentage points. During George W. Bush’s eight years, the gap grew to just over 5 points. But it widened rapidly during Obama’s tenure, with whites on average showing a 9.5 percentage-point preference for the GOP in the past five years.

Because those older than 65 are overwhelmingly white — 85 percent in Gallup’s estimate — the Republican move among white Americans has helped drive the older generation’s overall shift to the right.

Among the youngest voters, those aged 18-29, race also plays a significant part in a political shift, this one toward the Democrats. Whites make up only 54 percent of that age group, and non-whites lean heavily Democratic: 62 percent-25 percent among non-whites aged 18-29. The fact that non-whites make up a much larger share of the current under-30 generation than in past generations helps account for that group’s more Democratic flavor.

But race is not the only factor. Even among whites, Americans aged 18-29 are more Democratic than were previous generations, the Gallup numbers show. During the Bill Clinton years and on into George W. Bush’s second term, Republicans had an edge among young whites. That began to change in 2006, and Democrats have had the edge among them most of Obama’s tenure. Younger whites tend to hold liberal views on some social issues, such as same-sex marriage, and that has distanced them from the GOP.

AP Photo/Wisconsin State Journal, Craig Schreiner, File