Former advisor to Donald Trump Sebastian Gorka has slammed Joe Biden as a “coward” and said he is treating his likely opponent like “Voldemort.” Biden and Trump swept to victory in statewide nominating contests across the country last week, setting up a historic rematch in November’s general election despite low approval ratings for both candidates. Trump and Biden both focused on each other as the results became clear and in a victory speech at his Mar-a-Lago estate in Florida, Trump focused on Biden’s immigration policies and called him the “worst president” in history. Biden claimed in a st…