Then he throws away any chance of ever being seen as a respectable elder statesman again.
Well, he basically did that anyway with bringing up Palin and his stances after '08...
That's what I was going to say too. McCain "went there" enough in 2008, or at least was apathetic enough about Republican attacks on Obama during 2008 that he has since been seen largely as betraying his stance of moderate maverick who stood up to the irrationalities and exploitative politics of many Conservatives. Instead, he became that which he was seen as a bulwork against. I think McCain and the view America has of him can be summed up in his relationship with Jon Stewart. If you know that, you understand.
It is important to note that many of the seeds of the Obama smears and vicious myths were seeded in 2008, as were the seeds of the political infrastructure both in the GOP and with the voters which has since opposed Obama on everything with a zealotry born of the idea that they are right and righteous and the president is a leftist of the most extreme and unprecedented degree tied to so much evil, plotting evil, and that what he supports is terrible. (Run on sentence). The situation has deteorated to such a heinous degree now compared to 2008, but the seeds were planted. The situation here seems to be one where McCain takes what took until maybe 2009 or 2010 to reach that high water mark, and unleash it in that massive amount in 2008. I don't know if the enviroment of 2008 will accept it. I remember 2008 and the days before there were Tea Partiers dressed up in halloween costumes for a second American revolution. Obama Republicans were a very, very real thing, and living where I did I very much have a first hand knowledge of this. I was constantly hearing from life long Republicans I knew saying there were voting for Obama, and I live in a very small town in a very, very, very Conservative county. I suppose I don't know if the seeds of irrational vitriol were something that could be cultivated to such a 2009/2010 degree at this point and hastened acceptably and successfully, or if they would be too green and not ripe enough. At the same time, I do recall people who dug their feet in, and stated all the heinous things about Obama that were being propagated in 2008 and which would lay the foundation for the smearing and populist vitriol that would follow. They were themselves very fanatic, believing legitimately that Obama was a Muslim or a Socialist or a Kenyan and all the other things. They just seemed to not be organized, and to be overwhelmed by the outpouring in support of Obama, and they seemed to be not as widespread compared to what they'd become.
In short, everything of smear was there in 2008 and that is where it all started, but in the OTL it took until Obama became president to pick up as much steam as it did (though it already had massive steam as it was). I'm not sure if McCain could utilize it successfully at the time if he went even deeper into it, or if it might backfire given that there was a strong populist backing to Obama and such backing is vocal and public and is not as apathetic as it seems to have become and the Republican smears would come from the top down rather than from the bottom up while cultivated from the top down and propagated from the top down which has created and cultivated things like the Tea party.