Dr Whitehead, below left, said Mr Miliband, right, was the best person to bring voters back to the party in the south.
Mr Miliband, who declared his candidacy at the weekend, is considered more radical on environmental and social justice issues than his brother, former Foreign Secretary David, who is also standing. Other candidates are expected to include former schools secretary Ed Balls and backbencher Jon Cruddas.
Dr Whitehead, who is among 14 MPs to have thrown their weight behind Ed Miliband’s campaign, told the Daily Echo: “Ed has a more radical view of how the labour movement takes its message forward. It is a long-standing challenge for Labour to make its message resonate in the south of England and Ed represents the way I think the Labour Party should go in future.”
The MP suggested Labour had failed to address voters' concerns about housing, transport, environment, immigration and the labour force, all of which would have to be tackled to win back support.
The MP has said he knows who he wants to succeed Gordon Brown as leader – but will wait before revealing his preferred candidate so he can speak more freely about what Labour needs to do to rebuild its support in the south.