Vice President Dick Cheney is assuming the powers of the presidency for the second time in five years while President George W. Bush undergoes a medical procedure. Bush planned to hand over authority to Cheney on Saturday before he goes under anesthesia to receive a routine colonoscopy, a test to look for potential cancer. The same routine was followed when Bush underwent a colonoscopy in 2002. Saturday's procedure was to be performed at Camp David, the presidential retreat in Maryland's Catoctin Mountains. At the time, Cheney is expected to be at his home on the Chesapeake Bay in St. Michaels, Maryland, about 45 miles (70 kilometers) east of Washington. Two polyps were discovered during examinations in 1998 and 1999 while Bush was governor of Texas. In 2002, Bush had no symptoms and doctors recommended another test in five years. "Although no polyps were noted in the exam in 2002, age and history would suggest that there's a reasonable chance that polyps will be noted this time," said White House press secretary Tony Snow. "If so, they'll be removed and evaluated microscopically." Bush is 61. Snow, himself a cancer sufferer, said results would be available after 48 hours to 72 hours, if not sooner.