Washington Post: Liberal groups hoping to revive enthusiasm before the midterm elections are encouraging members to show up on the Mall on Saturday for a rally that they expect to draw tens of thousands of people. Their aim is to reclaim the sense of excitement that surged among left-leaning groups after the 2008 presidential race but more recently has belonged to tea party groups and other conservative activists. Conservative commentator Glenn Beck filled the Mall with tens of thousands of his supporters last month.