The rigors of the presidential campaign appear to be taking a toll on Sen. Barack Obama, whose closely shorn black hair appears to be increasingly gray. But when his 71-year-old Republican rival is questioning his experience, perhaps a little salt in the pepper is good.

“I’ve been running for president for 19 months, which explains the gray hair,” the 47-year-old presumptive Democratic nominee told supporters this week.

Zariff, a Chicago barber who goes by one name and who has been cutting Obama’s hair for about 15 years, said he first noticed gray about three years ago.

“It has showed up a little bit more, especially in the past year,” said Zariff, who has worked at the Hyde Park Hair Salon and Barbershop for nearly two decades.

But he demurred when asked if campaign stress is the cause. “Well, if he’s under any stress, I don’t notice it. He’s pretty smooth when it comes to that,” Zariff said.