The nation's largest labor union has lined up behind Joe Biden's presidential campaign, with the National Education Association on Saturday endorsing the former vice president for the Democratic nomination over his last remaining primary rival Bernie Sanders.

Joe Biden's presidential campaign is plowing $12 million into a six-state ad buy ahead of the March 10 and March 17 primaries, his largest single advertising effort of the 2020 campaign and a demonstration of his resurgent campaign's new financial footing.