Donald Trump came under fire for violent remarks targeting a high-profile Republican supporter of Kamala Harris Friday as the candidates held rallies in critical Rust Belt battleground states four days before the climax of a volatile US presidential campaign. More than 68 million Americans have already cast their ballots ahead of Election Day on Tuesday. Opinion polls show Trump and Harris running dead even, with victory depending on who prevails across the seven swing states, including Wisconsin and Michigan. Both held a full day of campaign events, concluding with rallies in Wisconsin’s larg…