Democrats led by an Arab-American lawmaker attacked President Donald Trump's "silence" on the rise of white supremacy Sunday as reaction to the New Zealand mosque massacre spilled into a heated US debate over religious and racial bigotry. With controversy swirling over Trump's tepid response to the massacre, White House chief of staff Mick Mulvaney was forced to deny any affinity between the president's anti-immigration rhetoric and the accused Christchurch shooter's extremist views. "The president is not a white supremacist," Mulvaney said in an interview with Fox News Sunday.