DETROIT (AP) - When President Donald Trump refused to outright condemn white nationalists in this week's presidential debate and urged his supporters to monitor polling sites, Portia Roberson was reminded of earlier eras when Black Americans were intimidated at the polls to deter them from voting. Roberson, a 51-year-old Black woman who lives in Detroit, found the comments chilling - but also felt a renewed resolve to vote. For many Black Americans and other people of color, Trump's comments in his debate with Democratic challenger Joe Biden were a harsh reminder that the nation has yet to fully grapple with systemic racism laid bare this year by protests against police killings of Black people, the coronavirus pandemic, and the resulting economic fallout. But they were also a call to action. "I hope that we take some of that frustration, anger and sadness that we've all been feeling for the better part of 2020, and use it to motivate ourselves to go to the polls and make sure we vote and vote for candidates who really reflect what Black folks need in this country," said Roberson, CEO of the Detroit nonprofit Focus: Hope. Trump tried to walk back his debate comments on Wednesday, but the moment when he told one far-right group to "stand back and stand by" had already been cemented in the minds of many Americans, experts and activists say. A day after the debate, the president said he didn't know the group but that it should "let law enforcement do their work." During the debate, he also urged his "supporters to go into the polls and watch very carefully because that's what has to happen." Eric Sheffield, a Black real estate developer in Atlanta whose parents hail from the Deep South, said Trump's comments reminded him of the Jim Crow era. "I...