I'd like some sources on that. I don't recall that from any PACs or the Obama campaign. Now maybe you are referring to individuals who supported Obama in that election, and I can't say that you're wrong. I sure didn't hear any of that sentiment from Obama supporters. Most of what I heard from that side were attempts to make McCain sound like a continuation of Bush.Maybe they are the same nuts who made the same claims about McCain when he was running against President Obama. Surely you remember.
I will also add that McCain took a hard line against supporters who questioned the legitimacy of Obama's candidacy. I respected that. He could have tried to fire up the kook fringe, but he took the high road. Flash to 2016, and Trump is living off of firing up the kook fringe. I think that speaks to their respective levels of character.