The 4th Democratic Presidential Debate: What You Should Watch For Impeachment looms over the latest Democratic presidential debate. Plus, Bernie Sanders takes the stage following a heart attack, and Elizabeth Warren continues rising in the polls. This episode: political correspondent Asma Khalid, political correspondent Scott Detrow, and national political correspondent Mara Liasson. Email the show at firstname.lastname@example.org. Find and support your local public radio station at npr.org/stations.