Education department chief Sir Michael Bichard is quitting his job six years before retirement, fuelling speculation that education secretary David Blunkett will be moved to a different ministry after the election.
Sir Michael, permanent secretary at the Department for Education and Employment, plans to leave at the end of May, after the forthcoming general election, to "seek out new challenges".
Sir Michael has worked closely with Mr Blunkett on a range of radical education policies, including the introduction of university tuition fees and the scrapping of student maintenance grants. Mr Blunkett is tipped to move to the Home Office.