The hand-wringing about whether Barack Obama is "electable" has reached the point of absurdity. The claim that Hillary Clinton's 9-point win over Obama in Pennsylvania "proves" that Obama can't carry the Rustbelt in a general election is completely baseless. But that hasn't kept the Clinton camp, the Rightwingosphere, and a bunch of TV talking heads just parroting the currently fashionable line of patter from pretending to believe it.
They haven't convinced the superdelegates (since Tuesday Obama has picked up three new endorsements to Clinton's one), and at least one major Clinton fundraiser is about to jump to Obama, but they've managed to spread an atmosphere of gloom. If you're looking for something to worry about, I suggest global warming. A McCain Presidency is indeed a horrible prospect, but then so is an asteroid strike. Neither is likely.
In Pennsylvania, the Clinton campaign and the Rendell machine produced a massive turnout and won the primary. That's to their credit.
But Barack Obama got almost twice as many votes as any other candidate in the history of the Pennsylvania Presidential primary. So — unless you think that Clinton voters came out specifically to vote against Obama, for which I haven't seen any evidence — the notion that he displayed "weakness among key demographics" in a way that threatens his electability in the general election really doesn't pass the giggle test, does it?
Two Democratic candidates excited the Pennsylvania Democratic primary electorate as it's never been excited before. One did somewhat better than the other. But either one, at the head of a unified Democratic Party and with the support of the Rendell machine, ought to stomp John McCain in Pennsylvania in November.
The same analysis applies to various voter segments. The African-American share of the turnout was somewhat smaller than might have been expected, and despite Obama's appeal to the young the proportion of the youth vote to the total vote did not markedly increase. But in absolute terms, both young people and African-Americans turned out in astounding numbers; it's just that older people and whites kept pace. How is that A Bad Thing?