White House official Tina Tchen was promoted to assistant to the president and chief of staff for first lady Michelle Obama, the administration said Wednesday. Tchen most recently served as deputy assistant to the president and director of the office of public engagement, and as executive director of the White House Council on Women and Girls, the White House said. She will still be the council executive director in her new position. "I am thrilled to welcome Tina to my team," Michelle Obama said. "Tina's tenure at the White House has focused on ensuring that communities across the country have...