Are these the voters you're referring to that Obama has more problems than McCain has with the GOP base?
Yes, those are the types. I know plenty of very partisan Democrats in my precinct that have sworn not to vote for Obama. This precinct went for Kerry by at least ten points. Obama cannot afford to lose these areas.
PA has a similar problem for the Republican party that they have in IL and WA. 1 county speaks for the entire state. In IL and WA, Cook an King counties respectively were won by both Gore and Kerry by a wider margin of votes than they took the entire state. If not for those counties those states would be solidly in the Republican column. In PA it's Philadelphia County. It stands to reason that if voters in that county show up on election day it looks good for the Democratic party.
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Catholic blue collar ethnic voters?" What other types of voters are there in PA? What's the breakdown look like? I just gave a hint by citing Philadelphia. There's more to an electorate than what's in your city, town, environment, social circle, or whatever and there's more to political beliefs than the ones that 1 individual has.