Clinton, who unsuccessfully ran for the Democratic nomination against then-Sen. Obama in 2008, has denied that she is interested in another bid for the White House.
She is stepping down from her post at the head of the State Department in January.
Buffett is not the only one who believes that the former first lady could make a political comeback in four years. Several lawmakers, ranging from Rep. Nancy Pelosi (D-Calif.) to Sen. John McCainJohn McCainDems fear Trump arguments on terrorism FULL SPEECH: Tim Kaine accepts Democratic VP nomination Retired admiral: It would be a disaster if Trump were the face of the U.S. MORE (R-Ariz.), have said as much. On election night last week, discussion of “Hillary 2016” went worldwide on Twitter.
Buffett is a prominent President Obama supporter, most notably of the president's proposed "Buffett Rule," which would raise tax rates on the wealthiest Americans.