Ed Balls should "fall on his sword" to allow Ed Miliband to move on from the Gordon Brown era, a leading historian has said.
In an interview with the New Statesman, political historian Anthony Seldon urged the shadow chancellor to step down and allow the Labour party to rejuvenate itself.
"After 20 unbroken years at the heart of politics, quitting in the next few months until, say, 2017 would undoubtedly benefit your leader, your party, your wife and even yourself," he said in an open letter to Balls.
"Ed Miliband would be a much stronger leader without you. Forgive me, but you stop Ed breathing fresh air.
"With you close to him, his breath will always be stale and smell of a toxic brand. Without a prolonged period out of the public eye, neither you nor the party will ever rid yourselves of the opportunistic, negative and bullying image of the Gordon era."
Balls is usually disliked by the public and he is strongly associated with the bullying, macho culture which pervaded Downing Street under Gordon Brown.
But he is also credited as an able economist who predicted the results of George Osborne's austerity programme and one of the few Labour frontbenches who angers David Cameron.
"Without you, Labour could present itself as a clean party, free of the factionalism and brutalism that so tarnished it when Brown was boss and you were his consigliere," Seldon wrote.
"If Labour loses in 2015, you will be blamed and your career will be damaged beyond repair. If it wins, you would return to the front bench in 2017 a redeemed and respected figure. You might even one day become leader, your long-held ambition."
Balls lost to Miliband in the leadership contest which followed the 2010 general election and only became shadow chancellor after Alan Johnson quit the role.
At one point Miliband refused to say whether he would be shadow chancellor going into the 2015 general election but he later U-turned and confirmed Balls would remain in place.