Environment Secretary David Miliband has been urged by a senior Labour MP to challenge Chancellor Gordon Brown for the party leadership.
Mr Miliband calls Mr Brown an excellent PM-in-waiting
Former minister Frank Field said Mr Brown was too closely associated with Tony Blair's government and that he had "indelibly smudged" policy.
The party should instead consider "jumping a generation", he wrote in the Guardian newspaper.
But Labour MP David Chaytor said a contest would "strengthen" Mr Brown.
Mr Field, MP for Birkenhead, said the party needed somebody who "shouts at the electorate that New Labour has already moved on to the next stage of its life".
He added: "Will that be best achieved by a candidate whose hands have been on the steering wheel for the last decade?
"Or will it come from the younger generation, in a candidate who is not linked in the public mind with what will soon be seen as stage one of New Labour's journey?
"Step forward, David Miliband."
Mr Brown is widely regarded as favourite to succeed Mr Blair after he resigns as prime minister and Labour leader later this year.
Mr Miliband has repeatedly dismissed questions about the leadership contest by saying he believes Mr Brown is an excellent PM-in-waiting, and would make an excellent prime minister.
But press reports suggest senior Labour figures have been trying to persuade him to change his mind.
Last week, Mr Miliband told BBC One's Question Time: "I predict that when I come back on this programme in six months or a year's time, people will be saying 'wouldn't it be great to have that Blair back because we can't stand that Gordon Brown'."
He then clarified his remarks to say that Mr Brown would be a "very successful" prime minister.
Mr Field, a former welfare reform minister, said the chancellor would have been "trounced" by Mr Blair had they fought for the leadership in 1994.
The apparent pact which persuaded Mr Brown to stand aside had created a "permanent instability" at the top of the party, he argued.
Asked on BBC Radio 4's World at One if personal grievances against Mr Brown had motivated his comments, Mr Field said: "I certainly don't feel that."
But voters might prefer "someone who was not in the Cabinet when we went to war in Iraq", such as Mr Miliband, he added.
However, David Chaytor, MP for Bury North, told World at One: "I think Gordon Brown's position would be strengthened if his record and programme for the future was tested through an election."
Left-wing John McDonnell is the only MP so far to declare he would run against Mr Brown for Labour leader.