Republican Senate Judiciary Committee Chairman Sen. Lindsey Graham announced on Sunday that he will call former special counsel Robert Mueller to testify before the committee, after Mueller  wrote a Washington Post opinion-editorial piece criticizing President Trump’s commutation of Roger Stone’s sentence.

Stone was convicted last November on charges, brought by Mueller, of lying to investigators regarding his connections to WikiLeaks and attempting to obstruct federal investigations.

The president commuted Stone’s sentence late Friday, prompting Mueller to write that Stone “remains a convicted felon, and rightly so,” adding, “I feel compelled to respond both to broad claims that our investigation was illegitimate and our motives were improper, and to specific claims that Roger Stone was a victim of our office.”

“Apparently Mr. Mueller is willing – and also capable – of defending the Mueller investigation through an oped in the Washington Post,” Graham tweeted in response.

Graham also noted that Democrats on the committee “have previously requested Mr. Mueller appear before the Senate Judiciary Committee to testify about his investigation,” stating “that request will be granted.”

Democrats had called for Mueller testify before the Senate in April of last year, just after the release of the Mueller Report. Graham responded at the time that he was “done with the Mueller Report,” and wanted to move on.

Apparently Mr. Mueller is willing – and also capable – of defending the Mueller investigation through an oped in the Washington Post.

— Lindsey Graham (@LindseyGrahamSC) July 12, 2020

Mueller led an investigation from 2017 until last year into alleged connections between the president’s campaign and Russia, in addition to Mr. Trump’s alleged efforts to cover up those connections, after the president fired FBI Director Jim Comey. The result of that investigation, The Mueller Report, found that the Russian government intervened in the 2016 election in order to benefit Trump.

However, the report did not find sufficient evidence that Trump’s staff “coordinated or conspired” with the Russian government. It also did not state that the president committed a crime, but did not “exonerate” him either.

“We identified numerous links between the Russian government and Trump campaign personnel — Stone among them,” Mueller wrote in his Sunday piece, adding that the investigation, “did not establish that members of the Trump campaign conspired with the Russian government in its activities.”

However, he asserted, “the campaign expected it would benefit electorally from information stolen and released through Russian efforts.”

Graham has led an investigation into the report’s origins, saying “we need to look long and hard how the Mueller investigation went off the rails.”

He has also subpoenaed intelligence officials such as former CIA director John Brennan and former FBI Director James Clapper.