[Read Mr. Nadler’s letter here.]

It is not clear whether there is a realistic chance that Mr. Barr and the Trump administration will take Mr. Nadler up on his counteroffer. But if the dispute moves to the courts, as seems likely, one of the issues that will arise is whether each branch has tried to accommodate the other branch’s constitutional needs.

In previous legal battles over the ambiguous line where Congress’s subpoena power ends and the president’s executive privilege power begins, courts have said that the Constitution requires both sides to negotiate in good faith to find a solution. If nothing else, Mr. Nadler is establishing a record that House lawyers can point to in any such litigation as they urge a judge to find that the administration’s position is unreasonable.

Mr. Barr made public a redacted version of the 448-page report on April 18. It detailed Mr. Mueller’s conclusion that despite ample contact, the Trump administration did not conspire with Russia to undermine the 2016 election. The special counsel did not reach a decision on whether Mr. Trump’s attempts to thwart investigators constituted obstruction of justice, expressly leaving that judgment to Congress.

[Update: Trump objects to Mueller testifying before Congress.]

House Democrats say they must judge the matter for themselves and need far greater access than Mr. Barr has so far allowed.

In his letter, Mr. Nadler complained that the administration has offered no rationale to justify the restrictions it has placed on access to the less-redacted Mueller report — only 12 members may now see it, and they must sign a nondisclosure agreement and leave their notes with the department.