The chairman of the House Judiciary Committee formally issued a subpoena on Friday demanding that the justice department hand over to Congress an unredacted version of Robert S. Mueller III’s report and all of the evidence underlying it by May 1.

The subpoena, one of the few issued thus far by House Democrats, escalates a fight with attorney-general William P. Barr over what material Congress is entitled to see from the special counsel’s nearly two-year investigation.

The chairman, Representative Jerrold Nadler of New York, asked for all evidence obtained by Mueller’s investigators, including summaries of witness interviews and classified intelligence. “My committee needs and is entitled to the full version of the report and the underlying evidence consistent with past practice,” Nadler said in a statement.

“Even the redacted version of the report outlines serious instances of wrongdoing by President Trump and some of his closest associates. It now falls to Congress to determine the full scope of that alleged misconduct and to decide what steps we must take going forward.”

Nadler’s deadline falls a day before Barr is scheduled to testify publicly before the Judiciary Committee in what is expected to be an explosive session where Democrats plan to excoriate Barr’s handling of the report and Republicans will urge their colleagues to accept that there was no criminality and move on. Nadler’s Republican counterpart on the committee, Representative Doug Collins of Georgia, blasted the subpoena as “wildly overboard” on Friday and encouraged Nadler to narrow its terms and extend the response time.

As written, he said, Nadler was demanding “millions of records that would be plainly against the law to share” because of investigators’ extensive use of a grand jury.

“The attorney-general offered up a 400-page report that he wasn’t bound to provide,” Collins said. “The attorney- general stands ready to testify before our committee and to have the special counsel do the same. Yet chairman Nadler disregards all of this good faith transparency without even taking the department up on its offer to review material under the redactions.”

Barr released to Congress and the public a redacted copy of the more than 400-page report on Thursday. Though the redactions were less extensive than some Democrats feared, the justice department had blacked out sections of the report that it said contained classified material, secretive grand jury testimony or information that would affect investigations still underway.

Democrats have been threatening to issue a subpoena for weeks, and the justice department on Thursday sought to head off the subpoena with a pledge to share more information with Congress.

Stephen E. Boyd, an assistant attorney general, wrote in a letter that the department would allow the bipartisan leaders of the House and Senate, as well as the heads of their judiciary and intelligence committees, to view a fuller version of the report beginning next week. But he said even that copy would still have secretive grand jury information blacked out because of legal requirements.

Given the sensitive nature of the information, Boyd wrote, “all individuals reviewing the less-redacted version” must agree to keep the newly unredacted information confidential. Nadler rejected the proposed accommodation as insufficient on Friday.