A day after it was revealed that special counsel Robert Mueller issued a letter to Attorney General William Barr regarding his summary of Mueller's investigation, CNN Legal Analyst Jeffrey Toobin says it shows that Mueller believes Barr swayed the summary in President Trump's favor.

The letter, which has since been made public, said that Barr's two-page summary of the investigation "did not fully capture the context, nature and substance of this Office's work and conclusions."

A Justice Department spokeswoman later told The Washington Post that Mueller and Barr also spoke over the phone regarding the summary, which was a "cordial and professional conversation" that "emphasized that nothing in the Attorney General’s March 24 letter was inaccurate or misleading."

Toobin, however, believes the language used in Mueller's letter illustrates something much different and illustrates Mueller's frustration with Barr's "deliberate distortion."

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“That is a scathing, outraged letter,” Toobin said, just before Barr took the stand to answer questions from the Senate Judiciary Committee regarding his summary. “Accusing the attorney general of completely distorting and lying to the public about what Mueller spent two years on.”

The letter went on to discuss the "public confusion about critical aspects of the results of our investigation" as a result of Barr's summary, which Mueller said threatened to "undermine a central purpose for which the Department appointed the Special Counsel: to assure full public confidence in the outcome of the investigation."

Toobin argued that Mueller's language did not appear to be a "polite letter among old friends."

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"That is an accusation of political interference in Mueller’s work,” he said. “That is not a routine letter in any sense of the word… let’s be clear about what Mueller is saying, that the fix was in and he is saying that Barr deliberately distorted his conclusions for the political gain of the president. That’s what that letter says in plain English," he continued.

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The letter has renewed calls from Democrats for Barr to resign. Barr has defended his summary of the Mueller report during his hearing with the Senate Judiciary Committee on Wednesday and will do the same on Thursday with the House Judiciary Committee, provided it is not postponed or canceled due to an ongoing debate about whether the staff committee's attorneys will pose questions to Barr.