According to new polls, the economy is the number 1 issue for American voters. But that's not just because the economy is slowing and mortgages are harder to come by. The real reason is middle-class families have exhausted the coping mechanisms they've used for over three decades to get by on median wages that are barely higher than they were in 1970, adjusted for inflation. Male wages today are actually lower than they were then; the income of a young man in his 30s is now 12 percent below that of a man his age three decades ago.

The first coping mechanism was moving more women into paid work. The percent of working mothers with school-age children has almost doubled since 1970 -- from 38 percent to about 70 percent. Some parents are now even doing 24-hour shifts, one on child duty while the other works. I call these families DINS - double income, no sex.

When families couldn't paddle any harder, we started paddling longer. The typical American now works two weeks more each year than 30 years ago. Compared to any other advanced nation we're veritable workaholics, putting in 350 more hours a year than the average European, more even than the notoriously industrious Japanese.

As the tide of economic necessity continued to rise, we turned to the third coping mechanism. We began taking equity out of our homes, big time. But now that home prices are sinking for the first time in decades, this final coping mechanism no longer keeps us afloat. As Moody's reported last week, defaults on home equity loans have surged to the highest level this decade.

In short, it's the economy, stupid. But not just the current slowdown. The underlying problem began around 1970. And any presidential candidate seeking to address it will have to think bigger than stimulating the economy with tax cuts or spending increases. The fact is, most Americans are still not prospering in the high-tech, global economy that emerged three decades ago. Almost all the benefits of economic growth since then have gone to a relatively small number of people at the very top. The candidate who acknowledges this and comes up with ways to truly spread prosperity will have a good chance of winning over America's large and largely-anxious middle class.

This column is adapted from Reich's weekly commentary on American Public Radio's Marketplace.