CHICAGO — Leaders of more than 20 leading liberal groups supporting both Hillary Clinton and Bernie Sanders are set to release a scathing letter on Tuesday that serves as a progressive call to arms against Donald Trump, imploring Americans to undertake a unified set of concrete steps to oppose the Republican front-runner — from protesting to organizing large-scale voter turnout efforts. “This is a five-alarm fire for our democracy. A hate-peddling bigot who openly incites violence is the likely presidential nominee of one of our nation’s two major parties. It is alarming and dangerous. Donald Trump’s candidacy is a threat...
