By Cameron Joseph - 09/26/12 11:30 AM EDT
Baldwin has had the momentum in her race against former Wisconsin Gov. Tommy Thompson (R), who led comfortably in polls a month ago but has fallen even with or behind her in recent surveys.
That's been in part because Baldwin’s had the edge on the airwaves after Thompson spent most of his money during the primary.
Crossroads has already been up in the state, but its return there is a sign it wants to even up the air fight.