Senator McCain yesterday dialed back criticism of Senator Obama’s years as a community organizer, calling the job “very honorable” even as he defended attacks at last week’s Republican National Convention by his running mate and Mayor Giuliani. The ridiculing by Governor Palin and Mr. Giuliani had prompted a backlash from groups that do community organizing, saying it was an attack on well-meaning Americans and a contradiction of Mr. McCain’s call to service. “I do not think it’s a negative. I think it’s very honorable,” Mr. McCain said yesterday on CBS’s “Face the Nation.” He said the criticism of Mr. Obama was a reaction to Democrats who had denigrated Mrs. Palin’s experience as a small-town mayor.