Two prominent Donald Trump supporters in Congress are going “to bravely go where no conservative and a Republican has gone in the last 30 years” — the black community — as new polls show the former president tripling his support among African-American voters. A sportscaster-turned-political-commentator will join the pair next week, The Post can exclusively reveal, for a swing-state event the black congressmen hope will galvanize support for Trump against a Democratic incumbent they characterize as old, racist and uniquely unsuited to the presidency.