Former Cabinet minister Stephen Byers has suggested he does not expect Labour "slavishly" to follow Chancellor Gordon Brown's agenda if he becomes leader.
Mr Brown should face a leadership contest, Mr Byers said
Mr Byers, an ally of Tony Blair, said he hoped there would be contest to succeed the prime minister when he steps down later this year.
"The Labour Party is not royalty and we don't go in for coronations," Mr Byers wrote in the Evening Standard.
It would be a "huge mistake to try to stifle debate", he added.
'Exchange of ideas'
Mr Blair has said he will step down as Labour leader before the party conference in September, with Mr Brown the overwhelming favourite to succeed him.
Even if there was not a contested election, Mr Byers said an "open debate" about the way forward for the party was essential.
"I know that an exchange of ideas worries some people. But it would be a huge mistake to try to stifle debate. The public wouldn't like it and the Labour Party would resent it," he said.
"Surely it is far better to have a discussion about priorities than the alternative, which would be a new leader behaving like Moses coming down from the Mount, presenting a set of policies cast in tablets of stone for us to applaud and slavishly follow."
Mr Byers, who resigned as transport secretary in 2002, did not mention Mr Brown by name in his article.
But he warned that the authority of the new leader could be undermined if there was not a proper contest.
He said: "We are not just choosing the next leader of the Labour Party; we are also deciding who will be the next prime minister of our country.
"We need to consider how the public would react if there was no contest."
"Will they question the authority of a prime minister who has not been voted into that position, even by his own party?"
Mr Byers also said he had "some sympathy" with the view that the burden of taxation was at "the limit of public acceptability".
"Given the record levels of public investment, our public services should now be reaching world-class levels - so we shouldn't be seeing only incremental changes, which is all too often the case at present," he said.
At the weekend, Mr Brown called for a "new" style of government, involving "the talents of the wider community".
He added: "The idea of the state being an overbearing state, which a lot of people have associated with the governments of the past, that cannot be the government of the future."
Instead he demanded a "servant state", prepared to listen to the people.