A quiz: How does the Democratic Party plan to lift stagnant middle-class incomes?

I realize that liberal-leaning economists can give a long, substantive answer to this question, touching on health care costs, education and infrastructure. But most Americans would not be able to give a clear answer — which helps explain why the party took such a drubbing last week.

The Democratic Party’s short-term plan to help the middle class just isn’t very clear. Some of the policies that Democrats favor, such as broader access to good education, take years to pay off. Others, like reducing medical costs or building new roads, have an indirect, unnoticed effect on middle-class incomes.

The fact remains that incomes for most Americans aren’t growing very fast and haven’t been for years. Median inflation-adjusted income last year was still $2,100 lower than when President Obama took office in 2009 — and $3,600 lower than when President George W. Bush took office in 2001. That’s not just because of the financial crisis, either: Last month was another solid one for job growth and another weak one for average wage growth, the latest jobs report showed.

We’re living through the great wage slowdown of the 21st century, and nothing presents a larger threat to the Democrats’ electoral fortunes than that slowdown.