"I think that Obama clearly never really wanted Biden to be running anyway," Duffy told "Fox & Friends."
"I think he knows he's a gaffe machine, I think he's very afraid that Biden might damage his legacy," Duffy added.
She was responding to a New York Times report that the former president repeatedly told Biden he didn't have to run.
“You don’t have to do this, Joe, you really don’t,” Obama told Biden early in 2019, according to the report, which added Obama "took pains to cast his doubts about the campaign in personal terms."
Biden, who leads President Trump in several polls on 2020 matchups, said he couldn't forgive himself if he passed up the opportunity to beat Trump. He initially thought he could beat Trump in 2016, but Obama reportedly pushed back because, in part, he thought former Secretary of State Hillary Clinton would be more effective in continuing his legacy, according to the report.
Duffy, on Saturday, added that Biden's age seemed to affect him more than Trump was affected by his own age.
"Donald Trump can outwork anyone and he's, I think, the only president who actually starts to look younger in office," she said.