People close to the president believe the political consequences of firing Mr. Atkinson could be devastating, especially when Mr. Trump needs all the Republican support he can get for a potential impeachment trial in the Senate.

Mr. Trump’s decision in May 2017 to fire Mr. Comey, who was leading an investigation into ties between Mr. Trump’s campaign and Russia, set off a firestorm that led to the appointment of the special counsel, Robert S. Mueller III.

The following month, after it became public that Mr. Mueller was investigating Mr. Trump for obstructing justice, Mr. Trump told the White House counsel at the time, Donald F. McGahn II , to have Mr. Mueller removed. That incident later became a central episode in Mr. Mueller’s report, and House Democrats are still considering using that incident in an article of impeachment on obstruction of justice.

Mr. Atkinson’s handling of the anonymous whistle-blower’s complaint was a major factor in the decision by House Democrats to initiate an impeachment inquiry. After conducting an investigation that led him to believe the complaint was credible, he forwarded it to the government’s top intelligence official, Joseph Maguire , who did not provide it to Congress in the time frame required under the law, but did allow Mr. Atkinson to alert lawmakers about the existence of the complaint.

In early September, Mr. Atkinson told Congress that Mr. Maguire had refused to hand over the document. Under pressure from Democratic lawmakers, Mr. Maguire then gave the document to Congress.

Mr. Maguire later acknowledged that he and his top lawyer had checked with the White House and Justice Department about whether he was permitted to turn the document over to Congress, saying that he was concerned that such an action could infringe on executive privilege issues.

Lawyers for Mr. Maguire and the Justice Department said that because Mr. Trump was not a member of the intelligence community, Mr. Atkinson did not have the jurisdiction to deliver the report.