If you vote with someone 89.2% of the time in a 7 year period, that makes you at the very least a believer in his policy. McCain isn't Bush III, since Bush is his own royal screwup.
McCain could turn out to be a even more royal screwup then Bush.
However, if you can say that Obama voted with party lines 100% of the time without evidence then I can say that he would follow the same policies as Bush.
“Today, we face essentially the same choice we faced in 2000, though it may be even more obvious now, because John McCain, a man who has earned our respect on many levels, is now openly endorsing the policies of the Bush-Cheney White House and promising to actually continue them. The same policies all over again? Hey, I believe in recycling, but that's ridiculous.”
-- Al Gore