Vice President Kamala Harris said that if former President Donald Trump is too exhausted to campaign amid a slew of interview cancellations, it raises questions about his fitness for the job of president.

At an energetic rally in Grand Rapids, Michigan, on Friday, Harris pointed out that Trump has been canceling interviews with just 18 days until the election.

In recent weeks, Trump has pulled out of interviews with mainstream media outlets including 60 Minutes, CNBC and NBC News . And on Thursday, the National Rifle Association said it was canceling an event with Trump because of campaign scheduling changes .

He is ducking debates and canceling interviews, Harris said to the crowd in Grand Rapids. And check this out; his own campaign team recently said it is because of exhaustion.

Harris was referring to a report by Politico on Friday that said Trump had backed out of an interview with the website The Shade Room and that one of his advisers had told Shade Room producers that he was exhausted and refusing [some] interviews, but that could change.

Waka Flocka Flame, a rapper who has been a vocal supporter of Trump , was reportedly offered up as a replacement interview instead of the former president.

Well, 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 said to cheers. Come on. Come on.

Asked about Harris comments, Trump told reporters on Friday that he isnt exhausted, called the vice president a loser and lied that she doesnt go to events.

What event did I cancel? I havent canceled, Trump said. She doesnt go to any events, shes a loser, she doesnt go to any events.

Trump pointed out that he had attended the Al Smith charity dinner in New York on Thursday, where he complained that he couldnt use a teleprompter . Trump also made an appearance on Fox & Friends Friday morning where he answered a 6-year-old boys question about his favorite animal by absurdly suggesting that Harris would get rid of cows if shes elected.

I love cows. But if we go with Kamala, you wont have any cows anymore, Trump told the kid.

Speaking to reporters, Trump said that after his Fox appearance, he made about 15 calls.

Ive done 48 days now without a rest, and Ive got that loser who doesnt have the energy of a rabbit, he said.

Tell me when youve seen me taking even a little bit of a rest, Trump added. Im not even tired, Im really exhilarated.