The next Labour party deputy leader must be a woman, Constitutional Affairs Minister Harriet Harman has said.
Ms Harman is concerned about the number of women MPs
Ms Harman told GMTV she wanted a team of three - a leader and two deputies, one of whom should be female.
Her interview came as John Prescott took up leadership of the country while Mr Blair holidays in Italy.
The Sunday Times has named Ms Harman as a potential successor to Mr Prescott, amid speculation the Deputy Prime Minister has lost party support.
The paper also named Northern Ireland Secretary Peter Hain and Education Secretary Alan Johnson as possible successors.
It said Mr Prescott has come under fire for holding onto his £133,000 ministerial salary and grace-and-favour homes despite being stripped of his department in the recent Cabinet reshuffle.
'Still a minority'
Women MPs are also said to be furious over his affair with Tracey Temple, the paper added.
Ms Harman told GMTV it was a "necessity" for the next Deputy Prime Minister to be a woman.
"I think that we have to have a team of men and women in the leadership looking to men and women who after all regard themselves as equals now," she said.
She added Labour faced a greater challenge from the Conservatives under David Cameron, who had done better at promoting new women MPs.
"The irony is that we had a very big new intake of Labour women MPs in 2005 but nobody knows who they are," she told the programme.
"The Tories have spotlighted their ... two or three new women. We've had a much bigger intake who are very talented and able and yet we haven't focused on them."
On Friday Ms Harman, in an with the Evening Standard, pointed out women were still a minority among Labour MPs.
"We are not men and women sharing power but women still trying to get more feet in the door."
She told fellow women MPs: "We need a few more rows about this; from time to time we need to kick up."