A week and a half after Dick Costolo announced that he would be stepping down from the CEO role at Twitter, the company´s board of directors has sent a shot across the bow of one of the expected front runner candidates to take the social network´s top job. The social micro blogging company´s search committee will only consider CEO candidates who are in a position to make a full time commitment to Twitter, the board said. That would seem to rule out Jack Dorsey, the company´s co founder who currently works as the CEO of Square and will be filling in as interim CEO of Twitter. Dorsey has said that he plans to remain at the helm of the payment processing company he co founded, but has not explicitly ruled out a bid for a permanent berth in Twitter´s top job.

Now the Twitter board has made it clear that he would have to depart Square if he wants to run Twitter. That is a rough proposition for Dorsey, especially since Square is reportedly planning to go public this year. As for the overall search process, Twitter´s search committee has contracted with executive search firm Spencer Stuart to evaluate internal and external candidates for the job. The board has not set a firm time frame for its hiring of a new CEO, saying that there is a sense of urgency to the process but that it will take its time to find the right person for the job. Whoever steps into the top spot at Twitter will have to contend with increased pressure on the company from Wall Street. Investors have been disappointed by Twitter´s revenue and user growth in recent quarters.