Harris targets Trump's age after report of exhaustion

Detroit: Kamala Harris questioned Donald Trump s fitness for office Friday as the oldest major party White House candidate in history faced speculatio...

Detroit: Kamala Harris questioned Donald Trump's fitness for office Friday as the oldest major-party White House candidate in history faced speculation that he is "exhausted" after backing out of a spate of interviews.

While he has been appearing on friendly TV networks, the 78-year-old Republican has canceled sitdowns with media outlets including NBC, CNBC and CBS. He has also refused a second debate with Harris, after being soundly bested in the first.

Politico reported that a Trump aide had told producers at a website negotiating an interview that the ex-president was "exhausted" and refusing some appearances -- a claim described by his campaign as "detached from reality."

But Harris, who turns 60 this weekend, hammered Trump over his health and resilience.

"If you are exhausted on the campaign trail, it raises real questions about whether you are fit for the toughest job in the world," Harris told supporters during a day of multiple stops across the swing state of Michigan.