I'd lean towards McCain's age myself. If whites in this country were that concerned about Obama's race he wouldn't even be in the position he's in. He certainly didn't reach the point he's at with just black votes. McCain's age doesn't mean he's unable to lead and as far as his health issues, well, less advanced age and a relatively clean past bill of health is no guarantee of long life. I've heard more about his age and health being mentioned as issues that could be an impediment towards his ability to lead than Obama's race.
I'm white, 52, my best friend of 40 years is black(When we became friends I caught it from both sides. Whites who called me a N-lover and blacks from the city where he had family who called me honky or cracker.) and my second wife was black. My sister-in-law is married to a black man whom I have a great relationship with and when their daughter calls me Uncle Dave, it makes me smile as much as when my own sibling's children call me that. I have two sister-in-laws who are Polish, another who's Italian, an Irish brother-in-law, a nephew who is a Jehovah's Witness and a gay cousin. I love them all. Except maybe the 2nd wife.
I've voted Democrat in every presidential election since Carter. Good man, nothing spectacular as a president. I wonder sometimes if Ford hadn't pardoned Nixon if he wouldn't have won that year. The only time I wasn't 100% certain about my vote was Clinton because I wasn't terribly familiar with him but I was less than fond of Bush Sr. While Clinton turned out to be a decent president, the economy during his time in office benefited greatly from the tech/dot com boom of that time. He still had his flaws but flaws are easier to ignore when everything's peachy.
Race, age, sex, culture or religion will never play a role in any decision I make. Only competency or a lack thereof. I won't give my vote to either candidate in this election because neither have said or done anything to make me believe that they can improve this country and elevate it to where it's been in the not so distant past.
Obama has reiterated the same refrain since the beginning of the year, worded slightly different here and there, but basically the same. Style without substance, as far as I'm concerned. He made a very good speech at the 2004 DNC which gave him national recognition and helped him get his foot in the door then realized after a short stint as a junior senator that all the resentment towards the current administration offered him the perfect opportunity to make a run at the presidency. His best argument? I'm not them. Sorry folks, change for the sake of change isn't always an improvement.
If McCain were the McCain from years past, I would actually be tempted to vote for him but he's not. It has nothing to do with his association with the party or Bush. I don't believe in guilt by association and all that silly warmonger garbage, as though no Democrat has ever presided over or sent troops into combat. He's just a fully assimilated Republican. He may still be less conservative than some/most, but he's not the same maverick willing to break away from the pack that he was once considered to be.
These two are the sorriest choices for president that I can remember and I don't think this country wins either way. It seems less like an election and more like a sporting event where one side is competing against the other to win the title.