The pro-Trump anchor made the claims during a segment about Mr Biden's presidential legacy on Sunday.
Conservative commentator and Turning Point USA founder, Charlie Kick, said Mr Biden appeared determined to prove to Mr Obama he "could do what you couldn't do when it comes to pandering to the liberal base and implementing progressive policy".
"Ah!" Ms Bartiromo replied.
"That's what it is. I know he's on the phone all the time with Obama and I'm hearing that he's running things from behind the scenes," she said.
While neither Mr Kirk nor Ms Bartiromo provided further detail on their sources underpinning the secret conspiracy, the dynamic between the Biden-Obama bromance was a long-running topic of speculation during the 2020 presidential campaign.
There was reportedly deep hurt in the Biden camp over Mr Obama's embrace of Hillary Clinton as his successor and a sense of pride driving Mr Biden to prove he was underestimated, according to Politico magazine investigation "What Obama Really Thought about Biden".
As Mr Obama reportedly warned of Mr Biden during the presidential primaries: “Don’t underestimate Joe’s ability to f**k things up.”
Speaking to one 2020 Candidate, he reportedly said: “And you know who really doesn’t have it? Joe Biden.”
While Ms Bartiromo's claims that Mr Obama is secretly pulling the strings of the current administration remain unproven, the former president's former officials have returned to key positions in the current White House.
Several Obama administration staffers returned to the Biden White House after adding massive wealth and corporate connections in the four-year interim between postings during Donald Trump presidency.
Chief of Staff Ron Klain, Domestic Policy Council Director Susan Rice, National Economic Council Director Brian Deese, and coronavirus response coordinator Jeff Zients all earned millions before returning to 1600 Pennsylvania Avenue, according to financial disclosure reports analysed by ABC News.
Mr Biden added so many former White House staffers to his own cabinet that the Associated Press asked if it was an "Obama reunion?"
The most high-profile comebacks included former Secretary of State John Kerry serving as special envoy on climate, and Kerry’s Obama-era deputy Antony Blinken to lead the State Department.
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