Why Obama's Desperate

It's the poll weighting.

This is an example of how Left Wing Media bias actually hurts Democrat candidates. It keeps from them vital information they need to campaign, and elevates unelectable candidates once the campaign moves from the media echo chamber to the voting booth.

This is why candidates use internal polls, and why their actions don't reflect trends in LWM polling.

Update:

Bob Tyrrell calls this notion the Taranto Principle.