WASHINGTON – Attorney General William Barr plans to deliver special counsel Robert Mueller's report to Congress and the public in "weeks, not months," a Justice Department official said Tuesday, offering the first indication of how soon the government would release more complete findings of the investigation.

The official, who was not authorized to comment publicly, said the department has "no plans at this time" to provide a copy of the report to the White House before it is made public.

Lawmakers intensified their demands for access to the special counsel's full report. Leaders of six House committees said in a letter to the attorney general that they wanted to see the entire document by April 2. They asked him to turn over the evidence Mueller's investigators gathered, saying the materials were "urgently needed by our committees to perform their duties under the Constitution."

Barr issued a four-page summary of that report Sunday, declaring that Mueller's 22-month inquiry had not found that Donald Trump or his presidential campaign conspired with Russian efforts to sway the 2016 election. On the separate question of whether Trump sought to thwart the investigation, Barr said he and Deputy Attorney General Rod Rosenstein determined that the president's conduct did not constitute a crime after Mueller's team declined to reach a conclusion on whether Trump obstructed justice.

Trump and his allies swiftly declared victory in the inquiry. Congressional Democrats said Barr's summary only heightened their interest in obtaining a fuller account of how Mueller reached his conclusions.

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A small team of Justice Department staffers is reviewing the report to determine which parts are based on grand jury testimony or would reveal information about other pending cases, subjects Barr said the department is required to keep secret, according to an official who was not authorized to speak publicly.

Senate Judiciary Committee Chairman Lindsey Graham, R-S.C., said Tuesday that he discussed the timing of the report's delivery with the attorney general Monday night. Graham said he asked Barr whether the document could be delivered within weeks, adding that Barr replied, "I think so."

Graham said lawmakers should give Barr "a reasonable amount of time to go through the report" and determine which parts can be released.

Sen. Dianne Feinstein, D-Calif., the ranking member of the Senate Judiciary Committee, sent a letter Monday to Barr calling for the report's release. "A four-page summary ... with no underlying evidence or findings, is not adequate to accomplish our constitutional, legislative, and oversight responsibilities," Feinstein said.

Democrats said they were particularly interested in Mueller's decision not to determine whether the president committed obstruction and how Barr could have reached his own conclusion so rapidly.

A Justice Department official said Mueller's team informed Barr and Rosenstein in a meeting three weeks ago that it could not reach a conclusion on whether Trump obstructed justice.

Mueller's indecision on obstruction, the official said, was unexpected.

“It was Bob Mueller’s decision not to reach a conclusion on obstruction,” the official said. “It was entirely Bob Mueller’s decision.”

Barr, nominated by Trump to replace Jeff Sessions, is all but assured to be called to testify before Congress to explain his action, along with the special counsel in what is shaping up as a protracted political fight that could spill into 2020 presidential election cycle.

In his letter, Barr said department lawyers would review the report to remove material that must remain secret, such as grand-jury-related information. Then, he said, he would review it again to determine "what can be released in light of applicable law, regulations, and Department policies."

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Democrats pointed to recent history to suggest they are entitled to more. In September 2016, the FBI released documents related to its investigation of Hillary Clinton's use of a personal email server during her time as secretary of state.

Justice Department officials have since turned over 880,000 pages of documents on the Clinton email inquiry, Rep. Adam Schiff, D-Calif., chair of the House Intelligence Committee, said in an op-ed last week. "There's no excuse to bury information on Trump Russia and counterintelligence."

Mueller's office began winding down its work. Prosecutors who work there notified federal courts that they were withdrawing from a case involving former Trump campaign chairman Paul Manafort, to be replaced by prosecutors from the U.S. attorney's office in Washington.

Contributing: Bart Jansen