The Pennsylvania Senate race is one of those data points for Democrats beginning to reverse the momentum for the midterms. Two new polls show Democrat Joe Sestak gaining, and one puts Sestak ahead of Republican Pat Toomey, 44-41.
This story notes that Sestak has a record of being a strong closer, so Toomey may have a serious fight on his hands. PPP suggests that Democrats have begun to unite behind Sestak and that independents are now moving away from Toomey and toward Sestak.
Toomey will have to keep reminding voters (and especially independents) what a vote for Sestak would mean: another vote for the Obama agenda. Sestak is trying to present himself as an open-minded voice of reason while casting Toomey as a Tea Party fanatic.
Toomey will need to fight back against that narrative. Toomey's website features an "Extremism Watch" that attempts to link Sestak to a radical agenda; however, the latest entry in that "watch" is from May. Emphasizing that message may help Toomey take back the momentum.
The grassroots right may find it more helpful to turn its attention away from certain long-shot Senate races and focus more on close Senate races like this one (or the ones in Nevada or Kentucky). At a certain point, elections aren't about sending a message or coming close: they're about winning. This is a race the GOP can win, but it has to keep its eye on the ball.
UPDATE: More reflections from Nate Silver.