The nation's biggest, richest and most powerful labor unions spent months organizing the "One Nation Working Together" rally at the Lincoln Memorial Saturday. With midterm elections approaching, they hoped to put on a show of political strength to energize struggling Democratic candidates. But even after giving it everything they had, they still weren't able to draw as many people as Glenn Beck's "Restoring Honor" rally in August. Why not?Because the labor movement is shrinking, aging and divided. Because the best program its leaders (and co-sponsors at the NAACP) could put together was one featuring Al Sharpton, Jesse Jackson, Richard Trumka, Van Jones and Harry Belafonte. And because George W. Bush is no longer in the White House. Put those factors together, and Big Labor's big march fell flat.