Candidates can't discount role of voter affluence, education

At first glance, the expectations game in Tuesday's Democratic primaries could appear counterintuitive.

Kentucky has a much higher percentage of African-American residents (7.3 percent) than Oregon (2 percent), yet Sen. Hillary Clinton is favored to win big in Kentucky, and Sen. Barack Obama is the heavy favorite in Oregon.

Why?

Affluence is another dividing line in this year's Democratic nomination battle -- and could well be the leading indicator in this week's showdowns.

Clinton's foundation in recent primaries has been blue-collar and rural white voters, and Kentucky offers them in large numbers, like its neighbors Ohio, West Virginia, Virginia and Tennessee.

The median household income in Kentucky is just shy of $34,000. Only 7 percent of households in the state report annual incomes in excess of $100,000, and Census Bureau data compiled by the Almanac of American Politics shows only 8 percent of the homes in Kentucky are valued at more than $200,000.

Obama, on the other hand, has performed strongly among more affluent Democrats and voters with college and post-graduate degrees -- which makes Oregon an inviting target. See what analysts have to say about the primaries »

In Oregon, the median household income is $41,000, and 10 percent of households report annual income in excess of $100,000. Twenty-six percent of Oregon homes are valued in excess of $200,000.

Comparing by education achievement: 25 percent of Oregonians have college degrees; 17 percent of Kentuckians do.

It is this disparity among more downscale white voters that Clinton argues would make her a stronger general election candidate, and that, more broadly, has some leading Democratic strategists watching for proof the Obama campaign understands the depth of the challenge.

"Barack Obama definitely has a problem coming out of the primaries," says veteran Democratic pollster Peter Hart. "You can look at Pennsylvania, you can look at Ohio, you can look at West Virginia and it tells you he has a lot of work to do with older voters, with white working class. ... A lot of work has to be done by the Obama campaign -- has to be done very, very quickly."

That said, even most Democratic strategists who believe Clinton would be the stronger general election candidate, at least based on today's data, see the prospect of Obama locking up the nomination in the next two weeks or so as a near certainty.

That calculation rests on simple math: Obama needs to win just 29 percent of the remaining delegates to clinch the Democratic nomination; Clinton needs to win more than 76 percent.

The breakdown: Obama now leads Clinton by more than 190 in overall delegates. And with just over 400 delegates still to be decided (189 pledged delegates to be allocated based on remaining contests and roughly 225 superdelegates who have yet to declare a preference), Obama needs fewer than 120 to clinch the nomination. Clinton would need 308.

Those calculations are based on the existing Democratic National Committee rules, which do not count Michigan and Florida results because those states voted in violation of party rules by moving their primaries up on the calendar.

All About Barack Obama • Hillary Clinton