President Biden and Donald Trump agree to debate in June and September. Also, Maryland Democrats back Angela Alsobrooks in the Senate race. Plus, Sen. Jon Tester vies for a fourth term in Montana. And Luke Russert discusses his book, "Look For Me There: Grieving My Father, Finding Myself." Andrew Weissmann, Simon Rosenberg, Angela Alsobrooks, and Sen. Jon Tester also join Lawrence O'Donnell.