Memo punches back after Obama team downplays Pennsylvania's importance.
Notes that Obama has lost six of the seven largest states, and says Pennsylvania's swing voters are crucial for a November victory.
"If Barack Obama cannot reverse his downward spiral with a big win in Pennsylvania, he cannot possibly be competitive against John McCain in November."
Earlier: Obama campaign memo calls the Keystone State "only one of 10 remaining contests, each important."
Plus: Pro-Obama governors release memo rebutting "'big state' spin," repeat themes in conference call.
Update: Counter-counter-punch from Obama team, which releases their own tounge-in-cheek annotation of the Clinton memo.
