For the most part, that tends to be how it works. But there's the separate question of resource allocation. If McCain is spending money to chase Pennsylvania, he's not spending that money in North Carolina, Virginia or Ohio. National trends are most important, but localized trends happen as well or else you wouldn't have local campaigns.
By the by... IN and NC will be an interesting lab test on whether a politician can literally buy the votes of an otherwise politically hostile state. He has poured millions and millions to IN, has visited there over 30 times. But it is still a state that hasn’t gone Dem since 64 and Bush won by 20. Sure, McCain’s opposition to ethanol subsidies don’t help.
Indiana reports first in the nation at 630 EST.. If they report in with McCain 10 or better, it will be our first sign that the polls were busted this cycle, like in ‘96.