Costolo, who stepped down as chief executive of at social media company in June, is now also planning to leave Twitter’s board, according to a report by Bloomberg. Costolo reportedly had remained on the board so that the transition would run more smoothly, but he plans to leave once they appoint a new chief executive at the end of the year.

Twitter’s CEO position has been temporarily filled by Jack Dorsey, the company’s co-founder and former CEO, while he simultaneously serves as CEO of mobile payment company Square, which he also founded.

As Twitter’s board of directors continues the search for a new chief executive, investor Chris Sacca took to Twitter to declare that Dorsey should maintain his CEO position at both companies. Twitter has been scrutinized lately for lacking product direction and new user growth, and Sacca believes that Dorsey has the “product vision” that the company needs to get back on track.

Despite Sacca’s strong support for Dorsey, the company is still considering its options. They supposedly have their eye on Renee James, current Intel President. She plans to leave the chip manufacturer at the end of next year and has reportedly said that she would like to serve as CEO at a top tech company. But Twitter’s board’s interest in James could be one way. James has a Twitter account, but has only tweeted a total of 14 times. It is unknown whether Intel has a policy against top executives tweeting.

Investors are hoping that a change of leadership will help Twitter’s growth prospects and stock price, but the company likely needs more than just a new CEO.

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