Jim Geraghty highlighted this tidbit from the National Republican Senatorial Committee yesterday:

Pennsylvania – Pat Toomey (R) 46.9%, Joe Sestak (D) 40%
The Democrats have spent over $3 million attacking Pat Toomey and he is in better shape today than he was a month ago. Because of the nature of the state, we think this race will be competitive to the end, but we will win.

The Hill also reported on the NRSC take on Pennsylvania:

The NRSC disputes that Missouri and Pennsylvania are battlegrounds, noting the DSCC spent more than $6 million in those two states since the middle of August and the GOP candidates still lead in the polls.
Democratic strategists, however, argued that Democratic spending in Pennsylvania has been countered by a deluge of television advertising from outside groups allied with the GOP.
Outside groups have spent about $5 million worth of advertising against Rep. Joe Sestak (Pa.), the Democratic candidate, according to a Democratic tally.

You can take a look at the spending breakdown by outside groups (on both sides) at the Washington Post. Outside groups have, indeed, been pumping lots of money into the Keystone State, but far and away in recent weeks the DSCC has led.

And despite it all, Pat Toomey leads by 9 points according to last week’s Rasmussen survey, and 7 points according to today’s Muhlenberg/Morning Call poll.