Here's a glimpse into Hillary's ad strategy in the final stretch of the Pennsylvania primary:
In most of Pennsylvania's markets, the only TV ad Hillary is running right now is a negative one -- the spot hitting Obama over his "small town" comments, a political ad buyer who tracks buys in Pennsylvania tells me.
The buyer says that as of this morning, that ad -- and no positive spots -- are running in the Pittsburgh, Erie, Johnstown/Altoona, and Wilkes-Barre/Scranton markets.
Meanwhile, the buyer says, in the Philadelphia and Harrisburg markets, Hillary's ad campaign is 50% negative -- she's running two spots, the new spot hitting Obama over oil companies, and another spot touting Hillary's plans to right the economy that doesn't mention Obama.
According to the buyer, the Philadelphia and Harrisburg markets add up to a bit over half the state's households.
Upshot: Nearly half the state's households are right now seeing only the "small town" spot, and the remaining half are seeing her economy spot and the oil spot hitting Obama, the buyer says.