Barack Obama, like any Democratic president, has serious IOUs to labor unions. And AFL-CIO President Richard Trumka, more than any other labor leader, is one ally he can't afford to alienate. About the last thing Obama wants, especially as his party faces heavy losses in congressional elections this November, is the subject of Trumka's lengthy track record of aggression and corruption to come up. Major media, for the most part, have obliged him in the wake of the round of speeches yesterday at the Milwaukee Area Labor Council Laborfest, making little or mention of inconvenient facts. It isn't as if Obama or top members of his administration are complaining.