It seems that Obama and McCain want to run a clean campaign with no ad hominem attacks but their supporters aren’t interested in doing that:

Barack Obama’s campaign distanced itself Saturday from a liberal talk show host who called John McCain a “warmonger” while introducing the Illinois senator at a North Dakota campaign stop the night before, after the McCain campaign called on Obama to denounce the comment.
Local talk show host Ed Schultz used the term to describe the Arizona senator while warming up the crowd in Grand Forks, N.D., before Obama’s arrival at the state’s Democratic convention.
“John McCain is not a warmonger and should not be described as such,” Obama spokeswoman Jen Psaki said Saturday. She added, “He’s a supporter of a war that Senator Obama believes should have never been authorized and never been waged.”
The campaign stressed that Obama was not present when the “warmonger” comment was made and that Schultz is not a campaign surrogate.

Though I would throw a bone to the Obama supporters and give his campaign a kudos for distancing themselves from such an unfair characterization.