AdvertisementWhite House Cites Pre-Existing Condition Case From Its Own RanksDecember 05, 2013Ari ShapirofacebookEmailMichael Robertson, then chief of staff of the Government Services Administration, testifies on Capitol Hill on April 16, 2012. Now chief of staff of the Cabinet Affairs Office in the Obama administration, Robertson has undergone treatment for stage IV colorectal cancer. (Getty Images)