Jeremy Corbyn appealed to critics to respect his "huge mandate" as Labour leader as he sought to assemble a shadow cabinet that could accept his radical left-wing programme.
Details of the top new-look top team are expected to be revealed over the next 48 hours, as Ed Miliband's successor gears up for his first appearance before the Parliamentary Labour Party in the Commons tomorrow.
The scale of the veteran MP's victory among party members as well as trade unionists and new-found supporters has quietened talk of a push by disgruntled moderates to oust him.
But the resignations of a string of senior figures who declared themselves unable to serve in his top team underlined the task he faced uniting the party behind his anti-war, anti-austerity platform.
John Woodcock, who chairs the Blairite Progress group, warned colleagues against "a fresh round of division and resentment between MPs who choose to be 'innies' and those who are 'outies'".
He added: "If we are to move on from here we must recognise how damaging it has been for Labour people - who have all basically wanted the same thing - to have knocked lumps out of each other for 20 years."
Mr Corbyn told the Observer it was important to recognise that his triumph - with 59.5% of the votes - represented "a huge mandate for a new democracy in the party".
"I think the membership and supporters will want and expect members of the parliamentary party to cooperate with the new leader and let us develop an effective strategy for opposing the Tories on the issues I outlined in my speech: welfare reform, trade unions, budget and so on," he said.
His first move was to keep Rosie Winterton on as chief whip, a crucial role likely to be a headache over issues such as military action in Syria, which Mr Corbyn opposes.
Among those tipped for the crucial role of shadow chancellor are Angela Eagle and his campaign chief and fellow left-winger John McDonnell, though his appointment to the role could alienate other potential allies.
Defeated leadership rivals Yvette Cooper and Liz Kendall are among those to have declared they would not take a role - with Tristram Hunt, Rachel Reeves, Chris Leslie, Emma Reynolds and Jamie Reed also returning to the backbenches.
Ed Miliband - whose resignation after leading the party to general election disaster in May provoked the contest - called on the party to join him in supporting Mr Corbyn but indicated that he too would not seek a return to the frontline.
It remained unclear whether Andy Burnham - who came a distant second in the leadership contest and had said he could work with Mr Corbyn - and Chuka Umunna - who issued a plea for unity - would accept jobs.
Mr Corbyn is not expected to take to the airwaves today - giving up a scheduled appearance on the BBC's flagship Andrew Marr Show to Tom Watson, who was elected the new deputy leader.
He will concentrate instead on forming his team and preparing for a busy first week - including Commons debate of Government anti-strike laws, a speech to the TUC annual conference and his first Prime Minister's Questions session.
Mr Corbyn has asked supporters to suggest what they would like him to ask Mr Cameron at the weekly set-piece, which he has promised will be a less confrontational encounter with him at the helm.
Downing Street said the PM - who has warned Labour under Mr Corbyn posed a threat to the UK's security and economic health - had telephoned his new adversary to congratulate him.