New Iowa poll: Biden lead shrinks as Warren, Buttigieg climb

06:02

A new Iowa poll shows Joe Biden is still leading the pack of 2020 Democratic candidates, though support has slipped three percentage points since March – and eight since December. Meanwhile, Elizabeth Warren and Pete Buttigieg surge to a near-dead heat with Bernie Sanders for second place. Larry Sabato, director at the University of Virginia Center for Politics, joins Alex Witt to explain why the poll should be a “warning flare” to the Biden campaign.