The director of the Press Complaints Commission (PCC) is standing down at the end of this month.
Stephen Abell is leaving to join PR consultancy Pagefield after more than a decade working for the newspaper and magazines watchdog.
The PCC has appointed Michael McManus, who has worked as a Government special adviser and as a director of PR firm Bell Pottinger, as its director of transition.
The body is under intense scrutiny as the Leveson Inquiry into press standards examines proposals for reforming the way newspapers are regulated.
PCC chairman Lord Hunt of Wirral said: "When I joined the PCC last year, Stephen and I agreed that we would work together until we were in a position to propose a new structure for self-regulation of the press.
"I have valued his assistance in this, and his professionalism in leading the PCC's staff as they continued their important work during a difficult period."
Mr Abell joined the PCC in 2001 and held a number of posts before becoming director in December 2009.
He said: "It has been a great privilege to work over the years with the committed, wonderful staff and board members of the PCC.
"I have been involved with the PCC for more than a decade, and I decided last year that it was time for a new challenge.
"First, I wanted to work with David Hunt in the development of positive proposals for a new structure of self-regulation. I believe we have now done that. I also wanted to give a full account of the work of the PCC to Lord Justice Leveson.
"I remain a firm supporter of enhanced self-regulation for the press, maintaining all that is good about the work of the PCC, and am confident that this will be achieved as a result of the Leveson Inquiry."
Lord Hunt laid out his proposals for a reformed PCC in evidence to the Leveson Inquiry last month.
Publishers would have to sign contracts with the new body, which would have a separate arm for enforcing standards and powers to summon witnesses, require access to documents and impose fines.
Mr McManus, who previously worked with Lord Hunt at commercial law firm Beachcroft LLP, has a brief to turn the PCC into a new body with a "comprehensive range of regulatory sanctions".