Twitter owner and CEO Elon Musk is searching for a new chief executive of the company, sources told CNBC’s David Faber.

Musk, who acquired the company for $44 billion in October, has previously said his position as CEO would be temporary. In court in November, Musk said, “I expect to reduce my time at Twitter and find somebody else to run Twitter over time.” However, on Sunday, he wrote in a tweet that “there is no successor.”

“The question is not finding a CEO, the question is finding a CEO who can keep Twitter alive,” he wrote.

The billionaire posted an informal poll Sunday asking Twitter users if he should step down as head of the company, and a majority of the 17 million respondents voted for Musk to leave his post. He said Sunday he would abide by the results of the poll.

Twitter polls are straw polls, which means they are not comparable to professional public opinion research. Malicious bots or inauthentic accounts may also be able to register a response to a Twitter poll.

Sources told Faber that Musk’s search for a new CEO has been ongoing and began before the Twitter poll was made.

Musk’s Twitter takeover has been rocky, as his leadership has resulted in massive staff cuts, a spike in racist hate speech, advertisers fleeing or slashing their spending on the platform, as well as the reinstatement of previously banned accounts.

The “Chief Twit,” as Musk has previously called himself, claims that Twitter usage has reached an all-time high since he took over, and that hate speech impressions have fallen.

The billionaire’s management of Twitter has raised concerns about his other ventures.

Musk has sold billions of dollars worth of Tesla shares this year to finance the Twitter takeover. He has also pulled in talent from Tesla, SpaceX and the Boring Co., including executives, engineers and attorneys, to assist him at Twitter. Musk is CEO of Tesla and SpaceX and founder of the Boring Co.

On Monday, Sen. Elizabeth Warren, D-Mass., wrote to the chair of Tesla’s board, Robyn Denholm, expressing concern that Musk and the board may have violated legal obligations to Tesla shareholders.

The lawmaker, who has sparred with Musk in the past over the idea of a wealth tax, asked the board to answer specific questions about the alleged misappropriation of Tesla resources and conflicts of interest resulting from Musk’s purchase of Twitter.

In a tweet Monday night, Musk said “the United States has definitely been harmed” by having Warren as a senator. A representative for Warren did not immediately respond to requests for comment.

Earlier this month, NASA Administrator Bill Nelson asked SpaceX President and COO Gwynne Shotwell whether Musk’s “distraction” at Twitter might affect SpaceX’s work with the space agency, NBC News reported. Nelson said she reassured him it would not.

Musk did not immediately respond to a request for comment.