Robert Winnett, the editor selected to run The Washington Post, will not take up that position, after reports raised questions about his ties to unethical news gathering practices in Britain.

Mr. Winnett will stay at The Daily Telegraph, where he is the deputy editor, according to emails sent on Friday to employees of the London-based newspaper and to staff members at The Post.

“I’m pleased to report that Rob Winnett has decided to stay with us,” read a message to Telegraph employees from the newspaper’s top editor, Chris Evans. “As you all know, he’s a talented chap and their loss is our gain.”

Will Lewis, the chief executive of The Post, confirmed the news in an email to employees.

“It is with regret that I share with you that Robert Winnett has withdrawn from the position of editor at The Washington Post,” Mr. Lewis wrote. “Rob has my greatest respect and is an incredibly talented editor and journalist.”

Mr. Winnett chose to withdraw himself from the position running The Post’s newsroom, according to two people with knowledge of the matter. He did not respond to calls and messages seeking comment.

Mr. Lewis said that The Post would run a search to fill the role. Past searches have been lengthy, culminating with an interview with Jeff Bezos, the Amazon founder who owns the paper.

Mr. Winnett’s decision to stay in Britain is the latest in a series of convulsions at The Post. Early this month, Sally Buzbee, the paper’s executive editor, stunned the newsroom by abruptly resigning. That coincided with Mr. Lewis announcing a plan to drastically remake The Post newsroom, including by installing Mr. Winnett as its permanent top editor.

In the weeks since, numerous articles about Mr. Winnett and Mr. Lewis have raised questions about their journalistic ethics and past conduct. Many journalists at the paper have become skeptical that the pair could lead an institution like The Post.

Mr. Bezos, who has owned the paper for over a decade, has been largely silent on the matter, though he weighed in with an email to senior editors this week reassuring them that the standards at The Post would remain high.

“That can’t change — and it won’t,” Mr. Bezos wrote.

Mr. Winnett earned a reputation as an unassuming newshound whose relentless pursuit of scoops earned him the nickname “Rat Boy.” But on Friday, several Washington Post journalists told The Times that, in light of the recent reports about him, they were relieved that Mr. Winnett would not be leading their newsroom.

“Rat Boy is out!” one journalist said in a text message.

Mr. Lewis told Post employees in early June that Mr. Winnett would take over as The Post’s editor after the U.S. presidential election in November. Matt Murray, the former editor in chief of The Wall Street Journal, would replace Ms. Buzbee in an interim role until then.

In his email on Friday, Mr. Lewis said that Mr. Murray would continue as The Post’s top editor until after the U.S. elections. He said that The Post was planning to put in place a new division, focused on service and social media journalism, sometime in the first quarter of next year. Mr. Murray was expected to take over the new division at the time Mr. Winnett’s appointment was announced.

Mr. Winnett’s decision is a major setback for Mr. Lewis, who has also repeatedly come under fire in recent weeks.

The Times reported on June 5 that he clashed with Ms. Buzbee over a decision to cover a court development mentioning him in a phone hacking case. Mr. Lewis has denied pressuring Ms. Buzbee. The next day, an NPR reporter said that Mr. Lewis had promised him an exclusive interview in exchange for ignoring a story about phone hacking. In response, Mr. Lewis called that reporter an “activist” and acknowledged having an off-the-record conversation with him.

Last week, The New York Times reported that Mr. Lewis and Mr. Winnett were said to have used fraudulently obtained records in news articles at the Sunday Times newspaper in London. The next day, The Washington Post followed up with a 3,000-word investigation into Mr. Winnett that traced his ties to John Ford, a private investigator who acknowledged using unethical methods to obtain big exclusives.

Much of the angst in the newsroom from those revelations has been expressed privately. But David Maraniss, a Pulitzer Prize-winning journalist at The Post, wrote on Facebook on Wednesday: “I don’t know a single person at the Post who thinks the current situation with the publisher and supposed new editor can stand. There might be a few, but very very few.”

Scott Higham, a Pulitzer-winning investigative reporter who left The Post in March, chimed in: “Will Lewis needs to step down for the good of The Post and the public. He has lost the newsroom and will never win it back.”

The search for Mr. Lewis was run by Patty Stonesifer, a widely respected tech executive who is a confidant of Mr. Bezos and the former interim chief executive of The Post. Ms. Stonesifer made an appearance at The Post newsroom on Friday to meet with employees on a variety of matters, including its new service journalism division, according to a person with knowledge of her visit.

Before the widening scandal enveloped The Post, Mr. Lewis expressed effusive praise for Mr. Winnett.

In remarks during a contentious meeting with employees this month, Mr. Lewis called Mr. Winnett a “brilliant investigative journalist” who would “restore an even greater degree of investigative rigor” to the newspaper, according to a recording obtained by The Times.

“I think really naughty days lie ahead with Rob here as well,” Mr. Lewis promised.