Union leaders' exit from DNC exposes 'mind-boggling' tensions inside Democratic party

As the Democratic party fights to rebuild from a devastating election defeat, the abrupt exit of the presidents of two of the nation's largest labor unions from its top leadership board has exposed simmering tensions over the party's direction. Randi Weingarten and Lee Saunders quit the Democratic National Committee, saying it isn't doing enough to "open the gates" and win back the support of working-class voters. Ken Martin, the new DNC chair, and his allies told the Guardian that the party was focused on doing exactly that. Weingarten, president of the 1.8-million-member American Federation of Teachers, resigned after Martin did…