A high-stakes political struggle over requiring voters to show photo identification at the polls is erupting in Minnesota, conjuring up emotional precedents from the notorious Jim Crow poll taxes to the old Chicago admonition to “vote early and often.” The determined Republican drive to pass a photo ID constitutional amendment as a needed deterrent to fraud — and the equally strong DFL effort to oppose it as a partisan ploy to suppress votes — has turned the ordinary driver’s license into a symbol of our national divide. “It’s like we’re back in slavery, only it’s all of us this time,” said Antoinette Oloko, an African-American woman at one of several protests against photo ID and news conferences at the Capitol in recent days. “We’ve had cases of ineligible voters, convicted felons, voting when they shouldn’t be,” said Dan McGrath of the pro-ID group Minnesota Majority, who has collected pictures of voters’ given “addresses” that turn out to be empty lots.