A leading Republican super PAC has booked nearly $50 million in midterm advertising to defend threatened suburban battlegrounds as part of a broader strategy to defend the party’s imperiled House majority.

Congressional Leadership Fund, the super PAC affiliated with outgoing House Speaker Paul Ryan, R-Wis., announced the advertising commitments on Tuesday, signaling more air cover was on the way as November draws near. The initial investment is directing $38 million in broadcast and cable television to 20 districts threatened with a Democratic takeover, with another $10 million in digital spots flowing to 30 targeted seats.