President-elect Joe Biden announced Tuesday he was nominating Samantha Power, a former Obama administration official and key unmasker of Trump campaign staffers, to a top position in his incoming administration. “Ambassador Samantha Power is a world-renowned voice of conscience and moral clarity — challenging and rallying the international community to stand up for the dignity and humanity of all people,” Biden said in a statement. “As USAID Administrator, she’ll be a powerful force for principled American engagement.”