Dick Costolo is to step down as CEO of Twitter following a long period of criticism which has seen him under fire for the company failing to hit revenue targets and the social networks growth slump dramatically.

Costolos exit was announced in a filing with the US Securities and Exchange Commission, which states that he will step down on 1 June, and continue to serve on the board of directors for the company.

“I am tremendously proud of the Twitter team and all that the team has accomplished together during my six years with the company,” said Costolo. “I am deeply appreciative of the confidence the board, the management team and the employees have placed in me over the years, and I look forward to supporting Twitter however I can going forward.”

According to one Twitter employee, Costolo received a standing ovation when he announced the news, suggesting that despite the criticism he faced, he still has the support of much of the company.

One of the original founders of the firm, Jack Dorsey, will serve as interim CEO, while also still acting as CEO for mobile payments company Square, which could well lead to complications.

“The future belongs to Twitter thanks in large part to Dick Costolos dedication and vision,” said Dorsey. “Dick has put a world-class team in place and created a great foundation from which Twitter can continue to change the world and grow.”

Board members Peter Currie, Evan Williams and Peter Fenton will be part of the search committee looking for a permanent replacement for Costolo, and will be considering both internal and external candidates.

Recent personnel changes mean there is no heir apparent to Costolos position within the company. Analysts have pointed to both head of revenue Adam Bain, head of product Kevin Weil and finance chief Anthony Noto as potential CEOs, but none are clear successors.

Interim CEO Jack Dorseys position at Square rules him out as a permanent replacement, unless he decides to abandon the mobile payments firm to return to the company he helped found. Other co-founders Biz Stone and Evan Williams are likewise engaged in other projects.

Looking further afield, Twitter may try to recruit an experienced tech CEO to restore confidence in the firm, such as Instagrams co-founder Kevin Systrom, or Yahoo CEO Marissa Mayer. However, given the current attitude towards the social network on Wall Street, drawing a high-profile name away from another company may prove difficult.

One thing is certain: Twitter needs to find a new leader quickly if it hopes to turn the company around and return to its former position as a dynamic, exciting firm that people were keen to invest in.