Republicans and Democrats are bitterly divided over federal agents wearing masks, as Congress works to avert another partial government shutdown. Facing Friday’s midnight deadline, lawmakers are locked in a debate over funding Homeland Security. And a central question is whether to ban face masks by immigration enforcement officers. The House Democratic leader says unmasking the federal agents is a “hard red line” in the negotiations. But most Republicans say the current political climate leaves the immigration officers exposed to harassment if their faces and identities are made public.