WASHINGTON — Investigators for the special counsel spent months trying to get answers from President Trump: what he knew about a meeting between senior campaign aides and Russians; about changes to the Republican Party platform making it more Russia-friendly; about his associates’ outreach to WikiLeaks as it prepared to publish Democratic emails stolen by Russian hackers.

After months of resistance, his lawyers finally turned over written answers in November to those questions and others. But the public has not seen them.

Now, the question of whether they become part of the available history of Russia’s 2016 election interference and its aftermath — along with whatever else the special counsel, Robert S. Mueller III, may have gathered — turns on Attorney General William P. Barr. Since Mr. Mueller submitted a nearly 400-page report on his investigation two weeks ago, Mr. Barr, his aides and other law enforcement officials have been reviewing it to determine which portions to provide to lawmakers and the public — and what to black out.

Democrats in Congress, who have demanded to see the entire document, have expressed growing impatience with Mr. Barr. And members of Mr. Mueller’s team have told associates that Mr. Barr failed to adequately convey findings that were damaging to Mr. Trump in a letter he sent to Congress two weeks ago laying out their chief conclusions.

Mr. Barr has promised to give lawmakers — by mid-April, “if not sooner” — as much of the report as possible, subject to several categories of necessary deletions. But much will turn on how expansively or narrowly he interprets those categories.

Grand jury information

The first category that Mr. Barr planned to black out is secret grand jury information. A federal rule of criminal procedure generally forbids disclosure of such material, like citing a witness’s testimony before the jury or a disclosing that a document was obtained with a grand jury subpoena.

Classified information
The second category Mr. Barr has identified for redaction is “material the intelligence community identifies as potentially compromising sensitive sources and methods.”

Current investigations
The third category Mr. Barr has said will be off limits to Congress is “material that could affect other ongoing matters, including those that the special counsel has referred to other department offices.”

‘Peripheral’ people
The fourth category Mr. Barr has said he will redact is “information that would unduly infringe on the personal privacy and reputational interests of peripheral third parties.”

Privileged information
There are several types of privilege that could come into play. One is executive privilege, a power of presidents to keep secret from Congress certain internal executive branch information, like communications involving the president or his close advisers and, sometimes, internal agency deliberations. Another is attorney-client privilege, the power to keep secret a client’s discussions with his lawyer.

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