WASHINGTON — As he exited the stairs of his "Straight Talk Express" campaign bus on a chilly March day in Iowa, Sen. John McCain carefully took one step at a time, his left hand gripping a rail and his right knee looking stiff.
A bum knee isn't surprising in a 70-year-old man -- particularly one whose right leg was shattered about four decades ago when his jet fighter was shot down over North Vietnam.
But his wooden movements, along with his age and appearance, are creating an impression about McCain's health that could be a liability for the Arizona Republican as he tries to persuade Americans to elect him president.
McCain brings to the campaign a body and mind with some heavy wear and tear, including a couple of bouts of cancer and the effects of years of torture. If elected, he would be the oldest person in history to enter the White House, and if he served two terms he would leave office an octogenarian.
Other presidential contenders have health issues, including Sen. Joseph R. Biden Jr.'s two brain aneurysms in 1988, Rudolph W. Giuliani's prostate cancer in 2000 and former Sen. Fred Thompson's lymphoma. But they are all younger and haven't experienced McCain's physical and mental agonies.
Voters should not worry, the senator's staff says. He passed a recent health exam with flying colors, they say, the results of which will be publicly released in coming weeks.
"We all have trouble keeping up with him," said Eileen McMenamin, communications director in McCain's Senate office.
Indeed, when life spans are lengthening and people in their 80s are running companies and marathons, McCain's age in itself shouldn't be an issue, some experts say.
"Don't give me that age business," said Dr. James E. Birren, a prolific medical author known as the father of gerontology, who still lectures at USC at age 89. "If the task requires speed, then you want the younger person. But if it requires wisdom, you want somebody old."
But McCain's health, much like his politics, is a complex matter.
McCain has twice developed melanoma, a potentially deadly form of skin cancer. He had four surgeries between 1993 and 2002: two to remove melanomas, one to remove skin lesions and one to treat an enlarged prostate.
