WASHINGTON – House Republicans have reserved more than $18 million in ad time in districts from California to Massachusetts as they look to protect their majority.

The ad reservation, from the independent expenditure arm of the National Republican Congressional Committee, could potentially include 25 congressional districts. The reservation includes a mix of seats currently held by Democrats and seats where Republican incumbents are facing strong challenges.

As with House Democrats, who earlier this year announced about $32 million in ad reservations, the NRCC could shift its spending to different districts or increase its spending as races develop. But the ad reservation offers an early idea of where Republicans think they will play offense and defense this fall.