Chuka Umunna has denied he is spearheading an internal-Labour Party "resistance" to a Jeremy Corbyn leadership, following accusations by John Prescott that he is being disloyal.
The shadow business secretary, along with shadow education secretary Tristram Hunt, plan to set up a new group of MPs called Labour for the Common Good.
To some, the new group is seen as the HQ of any future plot to oust leftwinger Corbyn as leader. Umunna and Hunt, who are both backing Liz Kendall for the leadership and have said they would not serve in a Corbyn shadow cabinet.
On Monday evening, Prescott attacked the pair, accusing them of wanting to split the party. The former Labour deputy prime minister, who is backing Andy Burnham for leader, likened Umunna and Hunt to the 'Gang of Four' of Labour MPs that quit the party in the 1980s to set up the SDP.
"They have launched another group. It's called the Labour Group for Common Good. Sounds nice. But what does it mean? You are organising a group inside the parliamentary party before you've even elected the leader, that doesn't sound very loyal to me," he said
However Umunna told The Huffington Post today the speculation around the group was "totally overblown and getting quite ridiculous" and accused Prescott of trying to "muzzle" internal party critics.
"I think generally we could do with a bit of calm pending the result. There is just one 'gang' as far as I’m concerned and that is the Labour Party – end of story," he said.
"As I said publicly several weeks ago, a split of our party – which has always been a broad church – is completely out of the question and would be totally counter-productive, as is any talk of a coup after we learn of the result. I also said it is important that whatever the result of this contest, we all pull behind whoever wins regardless of the successful candidate.
"However, the debate about the future direction of the party does not start and end with the leadership contest. The Parliamentary Labour Party [PLP], like other parties in the House of Commons, has a rich tradition of different groups that contribute to policy debate on how we translate our values into practice."
Umunna also hit back at the suggestion the creation of a group of centrist MPs was disloyal, given the number of more leftwing groupings within the Parliamentary Labour Party.
"Jon Trickett used to convene the Compass group of Labour MPs, John McDonnell convenes the Campaign group of MPs, and there are numerous trade union groups of Labour MPs which have all rightly sought to do this too. So the Common Good group of Labour MPs simply follows in that tradition," he said.
The shadow business secretary, who dropped out of the leadership race in the early stages of the race added: "I hear the Common Good group has been dubbed the 'resistance' to a particular candidate when nothing could be further from the truth, not least because we do not yet know who the new leader will be.
"In fact, MPs who have nominated all of the leadership candidates have agreed to be part of the group, which includes opinion from across the Labour spectrum. It is also worth adding that the MPs involved are all people who have a strong record of loyally voting with the Labour whip.
"The biggest challenge facing not just the Labour Party but centre-left parties across the Western world is how to build a fairer, more equal world in the context of globalisation and the surge of technological forces that are displacing and reshaping industry after industry – there has been insufficient discussion of this in the party.
"The primary aim of the group is to give Labour MPs a forum to discuss this - I cannot believe people are seriously suggesting we should shut down and muzzle debate once we have a new leader."
On Monday, Prescott dismissed Hunt as a "bright academic" who should have "stayed in the university" rather than becoming an MP.
And last year he made fun of Chuka Umunna's name, referring to him as "Chumbawamba".