Sir Keir Starmer has issued a plea with his party not to “descend into political infighting” ahead of Thursday’s local elections.
The Prime Minister is under increasing pressure over his leadership as Labour are expected to make heavy losses in the polls on May 7.
Health Secretary Wes Streeting has garnered the support of enough MPs to launch a leadership challenge, the Telegraph reported.
Meanwhile, Mayor of Manchester Andy Burnham has a plan to return to Westminster “within weeks” to do the same and has identified several seats where MPs could clear a path for him, according to the Guardian.
It is understood that Labour’s ruling National Executive Committee will not stand in Mr Burnham’s way as it previously did when he was prevented from standing in the Gorton and Denton by-election.
Mr Burnham’s supporters are said to hope the Prime Minister will stand down following the local elections, avoiding the need for a leadership challenge.
Energy Secretary Ed Miliband and former Deputy Prime Minister Angela Rayner have also been tipped as potential leadership challengers.
In a bid to save his premiership, Sir Keir has called on his party to be more “united” to make life better for working people.
Writing in the Observer, he said: “We have a choice. We could sink into the politics of grievance and division. Or we could rise to this moment – together – in a national effort that matches the scale of the threats and turbulence we face.
“I am talking about a national mission to become a stronger, more resilient, and more united nation, allowing us to take control of our future, raise our sights, and reach towards something better.
“When the nation rallied together to deal with Covid, the last government could have channelled that spirit to build a better nation.
“But instead, they descended into political infighting and let the country slump back to the old status quo. Not this time.”
He continued: “This government will reshape our nation. Over the coming weeks, through the King’s speech and beyond, we will set out our agenda of radical reform – with activist, interventionist government building a stronger and fairer country.”
Doubling down on his plans to forge closer ties with Europe, the Prime Minister said: “Recovery depends on rebuilding the strength of our economy to make us more resilient to these kinds of shocks in future.
“That means deepening our economic relationship with the EU.
“The world has changed since 2016. And Brexit today looks quite different. It has damaged our economy and there’s no doubt in my mind where the national interest lies.
“Britain must be at the heart of a stronger Europe on defence, on security, on energy, and on our economy. I will be at the European Political Community summit today to take this forward.”
Labour has been predicted to lose more than 75 per cent of the council seats the party is defending across the country in the upcoming elections.
Lord Hayward said Sir Keir’s party will be down some 1,850 councillors after the close on May 7.
