Graham's comments follow an op-ed by Mueller published Saturday in The Washington Post, in which the former special counsel defended his office's prosecution of Roger Stone and wrote that he is still a convicted felon and "rightly so" in light of President Donald Trump's commutation of Stone. Mueller was appointed in May 2017 to investigate Russian interference in the 2016 presidential election.
"Apparently Mr. Mueller is willing - and also capable - of defending the Mueller investigation through an oped in the Washington Post," Graham wrote on Twitter.
He added, "Democrats on the Senate Judiciary Committee have previously requested Mr. Mueller appear before the Senate Judiciary Committee to testify about his investigation. That request will be granted."
Senate Democrats have repeatedly pushed for Mueller to testify before the committee. Republicans in the Senate have said it's time to move on from the investigation, but previously Graham said, "I'm all good, I'm done with the Mueller report."
But in an exchange during a Judiciary Committee meeting last month, Graham expressed a willingness to call Mueller to testify, telling ranking Democratic Sen. Dianne Feinstein that it is "not an unreasonable request" to have somebody from the former special counsel's team come before the committee.
"I'm not adverse to having somebody from the Mueller team come and tell the committee what they did and how they did it, as a matter of fact I think that's a really good idea. I'm not so sure Mr. Mueller would be the best person now," Graham said.
And later in the hearing, Graham expressed his willingness to call Mueller himself.
"As to Mr. Mueller: If you want to call him, I will," Graham said. "I would just ask you to think twice about that."
Still, House Intelligence Committee Chairman Rep. Adam Schiff, a California Democrat, said Sunday evening he's skeptical of Graham's motivations.
"I suspect all Lindsey Graham wants to do is continue his counter-factual, that is that Donald Trump was somehow the victim when Donald Trump was the one inviting Russians to help him get elected in the first place," Schiff told CNN's Wolf Blitzer on "The Situation Room."
Trump on Friday commuted the prison sentence of his longtime friend, who was convicted of crimes as part of Mueller's Russia investigation that included lying to Congress in part, prosecutors said, to protect the President. The announcement came just days before Stone was set to report to a federal prison in Georgia.
Stone's commutation appears to have broken the floodgates with Mueller and his tight-lipped team after a year of silence about their investigation. Throughout the investigation, Mueller's office refused to comment except in a few rare circumstances. Andrew Weissmann, the special counsel's office prosecutor who led the investigation of top Trump campaign officials Paul Manafort and Rick Gates, began tweeting about Stone on Friday night.
Mueller, for his part, has been silent since he testified r