Kamala Harris’ road to the White House could hinge on whether she balances her messaging between reassuring voters about her own credentials to lead the nation, with the risk Donald Trump “could pose to American society and democracy,” according to a well-known columnist and political analyst. “As the voters’ verdict looms, the former prosecutor needs to press her case that Donald Trump is unfit for office,” Ronald Brownstein wrote Thursday in an op-ed for the Atlantic. He added that a growing consensus in Democratic circles suggests that the vice president is struggling to deliver “a sufficie…