House Judiciary Committee Chairman Jerry Nadler openly challenged Attorney General Bill Barr’s determination that Robert Mueller’s investigation did not produce evidence that President Trump committed obstruction of justice.

At a news conference Sunday evening in New York City he said, “This report does not amount to a so-called 'total exoneration,'” referencing Trump's tweet that the findings represented a “Complete and Total EXONERATION.”

Nadler added: “Congress must step in to get the truth."

The New York congressman, who at one point seemed to acknowledge a heckler trying to interrupt his statement, became the latest Democrat demanding that the Mueller report should go public in its entirety.

The findings, detailed in a letter from Barr, indicated that Mueller did not establish evidence Trump's team or any associates of the Trump campaign had conspired with Russia to sway the 2016 election, and did not establish a conclusion on whether the president had obstructed justice.

In a joint statement penned with House Intelligence Committee Chairman Adam Schiff, D-Calif., and House Oversight Committee Chairman Elijah Cummings, D-Md., he wrote: “It is unacceptable that, after Special Counsel Mueller spent 22 months meticulously uncovering this evidence, Attorney General Barr made a decision not to charge the President in under 48 hours. The Attorney General did so without even interviewing the President. His unsolicited, open memorandum to the Department of Justice, suggesting that the obstruction investigation was ‘fatally misconceived,’ calls into question his objectivity on this point in particular.”

Earlier Sunday Nadler said that he’ll soon seek testimony from Barr.

For his part, Trump declared a “total exoneration” based on the report, a summary of which Barr transmitted Sunday. Barr’s letter includes clear language that the Mueller probe did not find evidence of collusion with Russia during the 2016 election.

READ BARR'S LETTER

However, Mueller did not draw a conclusion on whether the president obstructed justice, saying the report does not conclude he committed a crime and also “does not exonerate him.” In turn, Barr and Deputy Attorney General Rod Rosenstein concluded the evidence from the case “is not sufficient to establish that the President committed an obstruction-of-justice offense.”

That line swiftly prompted complaints from Democrats – while also giving them an opening to challenge Barr, despite facing what amounted to a victory lap from Trump, his legal team and his political allies over a report that largely supported their “no collusion” mantra.

“In light of the very concerning discrepancies and final decision making at the Justice Department following the Special Counsel report, where Mueller did not exonerate the President, we will be calling Attorney General Barr in to testify before @HouseJudiciary in the near future,” Nadler tweeted.

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Nadler also said on Twitter there “must be full transparency” on what Mueller uncovered “to not exonerate the President from wrongdoing.”

“DOJ owes the public more than just a brief synopsis and decision not to go any further in their work,” he said.

Nadler further said that since Mueller did not exonerate Trump on the issue, “we must hear from AG Barr about his decision making and see all the underlying evidence for the American people to know all the facts.”

TRUMP TEAM TURNS TABLES AFTER MUELLER PROBE ENDS

The comments from Nadler underscore that Democrats have no intention of accepting Barr’s summary report as-is -- amid numerous calls for the full report's release -- or putting the collusion and obstruction issues to rest, as they continue to pursue their own congressional investigations.

Democrats on the same committee also said Sunday that it, “Seems like the Department of Justice is putting matters squarely in Congress’ court,” after the release of the report.

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Barr released a summary of Mueller’s findings on Sunday in a letter to leadership of both the House and Senate Judiciary Committees. The special counsel’s investigation, which lasted for nearly two years, did not find evidence that any members of the Trump campaign conspired or coordinated with the Russian government during the 2016 presidential election.

But after months of speculation regarding whether the president obstructed justice, beginning when he decided to fire former FBI Director James Comey, Barr revealed that Mueller, after making a “thorough and factual investigation” into the matters, “ultimately decided not to make a traditional prosecutorial judgment.”

This kicked the determination to the Justice Department.

“After reviewing the Special Counsel’s final report on these issues, consulting with Department officials, including the Office of Legal Counsel; and applying the principles of federal prosecution that guide our charging decision, Deputy Attorney General Rod Rosenstein and I have concluded that the evidence developed during the Special Counsel’s investigation is not sufficient to establish that the President committed an obstruction-of-justice offense,” Barr wrote, adding that the decision was “not based on the constitutional considerations that surround the indictment and criminal prosecution of a sitting president.”

Barr explained that the government would “need to prove beyond reasonable doubt that a person, acting with corrupt intent, engaged in obstructive conduct with a sufficient nexus to a pending or contemplated proceeding.”

“In cataloguing the President’s actions, many of which took place in public view, the report identifies no actions that, in our judgment, constitute obstructive conduct, had a nexus to a pending or contemplated proceeding, and were done with corrupt intent, each of which, under the Department’s principles of federal prosecution guiding charging decisions, would need to be proven beyond a reasonable doubt to establish an obstruction-of-justice offense,” Barr wrote.

Nadler’s committee is already leading an investigation into “alleged obstruction of justice, public corruption, and other abuses of power by President Trump,” which he announced earlier this month. Nadler requested documents and records from 81 individuals and entities connected, in some way, to the president.

Meanwhile, other House Democrats have aggressively ramped up their own Trump-related investigations, which are expected to include a network of committee probes and high-profile hearings that are likely to last well into the 2020 election year.

At this point, the House Intelligence Committee is probing the president’s foreign business dealings and Russian election meddling. The House Foreign Affairs Committee, led by Chairman Eliot Engel, D-N.Y., is probing Trump’s foreign business dealings as well.

Fox News' Frank Miles and Chad Pergram contributed to this report.