One potential benefit, she said, is that the furor surrounding Mr. Comey’s ouster may put a greater spotlight on Russia’s meddling in the election. The Clinton campaign struggled before the election to generate interest in Russia’s role beyond core Democrats, Ms. Palmieri said.

How big a role Mr. Comey played in Mrs. Clinton’s defeat is a subject of debate, even within her inner circle. In the immediate aftermath of the vote, she told donors, “Our analysis is that Comey’s letter raising doubts that were groundless, baseless, proven to be, stopped our momentum.” She has continued to emphasize the F.B.I.’s role. Her friends say she believes that but for Mr. Comey and the Russians, she would be president.

In a recent interview, Mrs. Clinton was asked how she felt when watching Mr. Comey tell Congress he believed it was inappropriate before the election to disclose the F.B.I.’s investigation of the Trump campaign’s ties to Russia, which began in July. She responded, dryly, “That was one of the high points of the last weeks.”

Other officials, however, said the F.B.I. intervention was one of a torrent of negative developments for the Democratic campaign, including the release of campaign emails by WikiLeaks, that sapped its momentum in the weeks after the third debate between Mrs. Clinton and Mr. Trump. “We had a lot coming at us, and it was one too many things,” Ms. Palmieri said.

In recent conversations, Democratic officials have faulted the Clinton campaign’s message and her use of a private email server as secretary of state. They have also cited structural impediments, like gender bias and Mrs. Clinton’s identity as an establishment figure in a “change election.”

Whatever the other factors, Mr. Comey has become a singularly baleful figure to people who worked on her campaign.

When Mr. Comey testified last week that he felt “mildly nauseous” at the idea that he might have swayed the election, John D. Podesta, who was the campaign’s chairman, wrote on Twitter, “The American public is getting mildly nauseous listening to Jim Comey.”