The Democratic National Convention in Charlotte, N.C., ended in a big whimper, much like President Obama’s term in office. In his keynote address on Thursday, the president struggled unsuccessfully to give the public a compelling reason to vote for him. The message of hope that worked in 2008 no longer holds up in light of the economic despair of 2012. The Bureau of Labor Statistics on Friday confirmed just how bad things are out there. The crucial number is not the official 8.1 percent unemployment rate or the 96,000 jobs created, but the 368,000 Americans who left the work force. For them, hope is gone.

This exodus from the job market drove the labor-force participation rate to a 30-year low of 63.5 percent, continuing a trend that has gone downhill throughout this so-called recovery. It’s a sign of how far down the path the United States is to having a permanent underclass, where the hope of achieving the dignity of gainful employment has been abandoned.

In the not-so-honest world of bureaucratic mathematical gimmickry, the exodus works in Mr. Obama’s favor. The 0.2 percent slip in workforce participation since last month is responsible for the illusory 0.2 percent improvement in the official unemployment rate. Had the participation number not changed from last month, the unemployment rate would have been 8.3 percent. If job-market participation had remained at the historic level of 65.7 percent, the official unemployment rate would be 11.2 percent.