My whole life, I've been a fairly moderate Republican, and I've always voted for the Republican for President. (The one time I didn't was in 1992, when I was at sea and didn't get my absentee ballot until 2 days after the election; I would have voted Republican had we gotten the mail in time.) I was never a doctrinaire Republican, though; I've always considered myself a realist with a Machiavellian perspective. I'm actually fairly idealistic about my realism.
Due mostly to good staffers who understood how the world really works, Republicans always seemed to be much better at getting elected and governing. (While many don't like our current electoral system, I actually think that the skills needed to win an election translate fairly well into what's required to run a government.) That theory worked fine until the mid-90s; since then, the Republican Party has been taken over by Evangelicals whose idea of good staff work seems to have been "pray harder". President Clinton had generally competent staff, but then the Gore and Kerry campaigns were so badly run that I started to despair that realists had been forced out of government service into the private sector for the foreseeable future. I hoped that the nominations of the best two candidates from both parties this year would show me things have changed. So far, I haven't been too impressed.
Up until the conventions, I noted that Sen. Obama's campaign was much better run than the McCain effort; Sen. McCain would repeat gaffes from one speech to another, and his responses to attacks by Sen. Obama seemed pretty lame. I was at the point where I was about to move from the "leaning McCain" category to "Undecided" or even "leaning Obama". During the last three weeks, however, things seemed to have changed -- and not for the better. While Sen. McCain made an inspired choice for Vice President (really, the only one that would give him a chance to win), the reactions of the Obama campaign show that they're going downhill rapidly, and the staff work for the McCain camp hasn't really gotten any better. (Examples: Sen. Obama comparing apples to dump trucks when talking about his "executive experience", and Sen. McCain turning Gov. Palin's E-Bay comment from something that was "technically true" to an outright falsehood.)
Sen. Obama's loudest supporters, on the other hand, have gone from bad to really bad since the Palin nomination. While modern "hatred" of politicians seems to have really taken off with the hatred of many conservatives for the Clintons, I believe the Left has surpassed that with their barely restrained, yet unacknowledged, hatred of many Republican politicians. (The haters on the right seem to be willing to freely admit their hatred for Sen. Obama.) It came to a head with many normally reasonable progressives showing themselves ready to believe even the most fantastic rumors about a woman they'd never spent a minute thinking about up to a few days before; that, I believe, it the epitome of hatred. Why is this important? Because these people are going to have a voice that will be heard by a future Obama Administration, and I've become much less likely to support Sen. Obama knowing that his most unrestrained supporters are so full of hate. Sen. McCain, as a moderate through most of his career, seems to attract more realistic and reasonable supporters (as evidenced by so many Evangelicals threatening to sit the election out if he was nominated). While I think Sen. Obama himself has remained admirably above the fray (notwithstanding his peevish "outrage" at Mitt Romney saying "...there has never been a day when I was not proud to be an American" while refusing to admit that the McCain attack on him for his "lipstick on a pig" comment had just as much viability), his supporters have sunk to a new low, and I think it'll be hard for him to get the debate back on track.
That being said, I think the election is still Sen. Obama's to lose. I think that Gov. Palin will exceed the very diminished expectations of her in the debate and set-piece interviews, but that Sen. McCain's age will show in the Presidental debates, and Sen. Obama will be a clear winner in those. That, plus all the new voters being registered by Democrats, will tip the scale in Sen. Obama's favor. I actually wouldn't mind that outcome too much, as long as the Republicans can keep at least 41 Senate seats. I think a McCain Presidency with a Democratic-controlled Congress would be the best outcome, but any outcome that doesn't hand complete control of the agenda to one party (and includes Walt Minnick beating my Congressman, Bill Sali) is OK with me -- the country is strong enough to survive 4 years of an Obama Presidency. His hate-filled supporters will unintentionally help make sure that he's not re-elected unless they quickly learn that such hatred doesn't play outside of their own echo chambers.