She said that instead, the magazine should have reserved that coveted honor for the whistleblower who reported on President Trump's July call with Ukraine and set off a Democrat-led impeachment effort.
"I actually wanted it to be the whistleblower this year to be the person of the year. I think it's a more salient and timely choice," McCain said.
McCain later added that she didn't think Thunberg "earned" the honor in the same way that the whistleblower did.
Her comments came after the president panned TIME's choice on Twitter, claiming that the 16-year-old climate activist had anger problems.
"It's hard for me to talk about Greta Thunberg because she's 16 and I still don't believe in attacking underage people," McCain said.
She also suggested Trump was envious of Thunberg.
"I'll just say to Donald Trump, 'Green is not a good color. It clashes with orange,'" Behar said.