A day after Elizabeth Warren acknowledged that she told two Ivy League schools she was Native American, her campaign began scrambling to allay the concerns of supporters about her handling of the issue, while political observers questioned why she’d let the incendiary issue smolder for so long. In a email to supporters, Warren sought to explain why she couldn’t back up claims that she is a Native American with proof of ancestry - a federal requirement when universities report their diversity data - and tried to rally her base by characterizing the backlash as a Republican-fueled personal attack.