Republican strategists worry that the party may not be able to win a Senate majority again, and they almost certainly will not be able to significantly expand their seat total in the chamber. And in the House, a historic seven incumbents have lost their primary races. What's behind the wave?READ: Senate Republicans Face Uphill Fight To Hold MajorityThis episode: campaign correspondent Asma Khalid, congressional correspondent Susan Davis, and national political correspondent Mara Liasson.Connect:Subscribe to the NPR Politics Podcast here.Email the show at nprpolitics@npr.org.Join the NPR Politics Podcast Facebook Group.Listen to our playlist The NPR Politics Daily Workout.Subscribe to the NPR Politics Newsletter.Find and support your local public radio station.Learn more about sponsor message choices: podcastchoices.com/adchoicesNPR Privacy Policy