Twitter chief executive Dick Costolo is stepping down and will be replaced on an interim basis from July 1 by co-founder Jack Dorsey, the company said Thursday.

The move comes with the one-to-many messaging platform struggling to boost its user base after a much-anticipated public offering in 2013.

Costolo guided the San Francisco-based firm through its initial public offering, but growth has been disappointing and the company has yet to show a profit.

A Twitter statement said Costolo would remain as a member of the Twitter board and that Dorsey would stay as CEO of Square, the financial technology group he founded, during the search for a new chief executive.

Twitter said it formed a committee that will work with “a leading executive search firm to assist in conducting a global search which will consider both internal and external candidates” for CEO.

Dorsey said in the statement: “The future belongs to Twitter thanks in large part to Dick Costolo’s dedication and vision.”

In its latest earnings report, in April, Twitter said it had a net loss in the quarter of $162.4 million.

The company said the number of active monthly users rose above 300 million, but that figure has been growing a pace too sluggish for many investors, and below rivals in social networking.