Chris Jennings, a top adviser to President Barack Obama who played a key part in the rollout of his signature healthcare law, is leaving the White House for health and family reasons, an aide told Reuters. Jennings, who previously served in the Clinton administration, was brought on board last year before the flawed rollout of the program created one of the biggest political problems Obama has faced since entering office. "Chris served the country at a time when he was needed most," White House chief of staff Denis McDonough said in a statement.