Two basic facts will tell you most of what you need to know about the political picture today.

Fact One: The unemployment rate is the most important of all leading political indicators.

Fact Two: If the August unemployment number to be announced Friday tops 9%—which seems highly likely—the jobless rate will have been above that level for 16 straight months. Already, the U.S. is mired in the longest such stretch of 9%-plus joblessness in more than a quarter of a century.

There is little mystery, then, about why Democrats are in trouble. The party in power is inevitably blamed for so much bad news on the one economic subject that most concerns average Americans.

Yet the political debate on this point, which focuses on what can be done to get Americans back to...