Scoop: Democrat Senate Super PAC targets 4 Republican seats

The Democrats' main Senate super PAC is booking another $54 million in TV ads for the midterm campaign's final stretch, targeting four Republican-held seats. Why it matters: The new reservations offer a roadmap to where Democrats think they can flip seats. Republicans' last major advertising reservation was aimed largely at defending incumbents — and protecting the GOP "red wall" to preserve their majority. By the numbers: Senate Majority PAC, the super PAC aligned with Senate Minority Leader…