House Intelligence Committee Chairman Adam Schiff called Wednesday for Attorney General Bill Barr to resign, seizing on a new report that Special Counsel Robert Mueller expressed concerns about Barr's public summary of the Russia investigation findings.

Schiff, D-Calif., who long promoted allegations of Trump-Russia collusion, already has blasted Barr’s handling of Mueller’s report for weeks -- as he also faced GOP criticism after the report itself did not find evidence of such a conspiracy. But Schiff took his criticism a step further Wednesday, calling for Barr's resignation just minutes before the AG was set to appear for Senate testimony.

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“Barr’s answer to @RepCharlieCrist, denying knowledge of Mueller’s concerns over his summary, was deliberately false and misleading. If he were an ordinary citizen, it might be considered perjury. As our top law enforcement official, it’s even worse. He must step down,” Schiff tweeted Wednesday morning.

During an April 9 hearing, Crist had asked whether he knew what prompted reports that Mueller prosecutors were frustrated with his initial summary. Barr said he did not.

Schiff's comments come after The Washington Post on Tuesday night first reported that Mueller contacted Barr, both in a letter and in a phone call, to express concerns after Barr released his four-page summary of Mueller’s findings in March. Mueller pushed Barr to release the executive summaries written by the special counsel’s office.

However, according to both the Post and the Justice Department, Mueller made clear that he did not feel that Barr’s summary was inaccurate. Instead, Mueller told Barr that media coverage of the letter had “misinterpreted” the results of the probe concerning obstruction of justice.

“The summary letter the Department sent to Congress and released to the public late in the afternoon of March 24 did not fully capture the context, nature, and substance of this office’s work and conclusions,” Mueller told the DOJ. “There is now public confusion about critical aspects of the results of our investigation. This threatens to undermine a central purpose for which the Department appointed the Special Counsel: to assure full public confidence in the outcome of the investigations.

In a statement to Fox News, DOJ spokesperson Kerri Kupec noted that Mueller had not faulted the accuracy of Barr's summary, and offered more details on Barr's actions.

“After the Attorney General received Special Counsel Mueller’s letter, he called him to discuss it," Kupec said. "In a cordial and professional conversation, the Special Counsel emphasized that nothing in the Attorney General’s March 24 letter was inaccurate or misleading. But, he expressed frustration over the lack of context and the resulting media coverage regarding the Special Counsel’s obstruction analysis. They then discussed whether additional context from the report would be helpful and could be quickly released."

Kupec added: "However, the Attorney General ultimately determined that it would not be productive to release the report in piecemeal fashion. The Attorney General and the Special Counsel agreed to get the full report out with necessary redactions as expeditiously as possible. The next day, the Attorney General sent a letter to Congress reiterating that his March 24 letter was not intended to be a summary of the report, but instead only stated the Special Counsel’s principal conclusions, and volunteered to testify before both Senate and House Judiciary Committees on May 1st and 2nd.”

But Democrats, including Schiff, pushed back, suggesting Barr had misled lawmakers in his testimony in early April.

"I note with interest AG Barr’s 4/10 Senate testimony," House Judiciary Committee Jerrold Nadler, D-N.Y., wrote. "'Q: Did Bob Mueller support your conclusion? A: I don’t know whether Bob Mueller supported my conclusion.' Now it appears that Mueller objected in this 3/27 letter."

Also Tuesday night, Sen. Chris Van Hollen, D-Md., wrote that Barr “must resign” because he “misled me, the Congress, and the public.”

In March, Mueller transmitted his report to the Justice Department for Barr’s review, marking the end of his nearly two-year-long investigation into Russian meddling and potential collusion with Trump campaign associates during the 2016 presidential election. Two days later, Barr released his summary of the principal findings in Mueller’s investigation.

Barr, in a four-page summary, said that the special counsel found no evidence of collusion between members of the Trump campaign and Russia. The special counsel was also leading an obstruction of justice inquiry into the president but ultimately did not come to a conclusion on the matter. Instead, Barr and Deputy Attorney General Rod Rosenstein determined the evidence was not sufficient to charge the president with an obstruction of justice offense. That decision prompted intense scrutiny for Barr from congressional Democrats.

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But despite the special counsel's findings of "no collusion," Schiff has maintained that there was collusion "in plain sight," citing the controversial meeting at Trump Tower with Donald Trump Jr., Jared Kushner, former Trump campaign chairman Paul Manafort and a Russian attorney. Schiff has repeatedly pushed the collusion claims, even to the point that Republicans on his own committee called for him to step down from his post as chairman.

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On Tuesday, a dozen Democratic senators also called for the Justice Department inspector general and Office of Professional Responsibility to investigate Barr's handling of the Mueller report. Barr is testifying Wednesday before the Senate Judiciary Committee.

Fox News' Gregg Re contributed to this report.