McConnell: U.S. dealt with sin of slavery by electing Obama; Biden recalls his working relationships with segregationists; Biden campaign defends comments: Biden didn't praise segregationists, but there was civility involved; Nadler: Dems would "destroy" WH immunity argument in court; Hicks about to wrap closed-door testimony on hill; Trump returns to WH after 2020 rally filled with 2016 attacks; Warren grabs Sanders' attention as she soars in new poll; Sanders tells corporate America: "I welcome your hatred"; Warren campaign: "we don't pay much attention to polls"; Trump delivers on coal promise, rolls back Obama-era policy; "Miracle on the Hudson" pilot testifies on Boeing 737 Max airliner, says he had trouble landing in simulator via Knit