Columnist Seumas Milne is to depart The Guardian "on leave" to become executive director of strategy and communications for the Labour Party.
The former comment editor's departure comes shortly after it was announced Patrick Wintour (pictured) will be moving from political editor to become diplomatic editor.
Wintour has been political editor of The Guardian since 2006 and previously held the same position at The Observer. He first joined the newspaper from the New Statesman in 1983.
The Guardian has advertised for Wintour's successor. It is seeking someone with "demonstrable experience on a national newspaper, website or magazine", with an "understanding of social media and multimedia a strong advantage".
Milne was previously comment editor of The Guardian. He left that role in 2007 to become a full-time columnist and associate editor of comment.
According to Wintour's report on Milne's departure, he is to join Labour on 26 October "on leave", "suggesting at a point in the future he will be free to return".