Andy Burnham is set to be installed as Prime Minister in just three weeks – despite having the feeblest mandate in British political history.

The self-styled 'King of the North' is on course for a 'coronation' next month after Keir Starmer dramatically resigned less than two years after his landslide election win.

But Daily Mail readers led the call for an early election on Monday night, with 89 per cent of 60,000 online votes telling Mr Burnham to go to the ballot box.

Wes Streeting ended speculation about a serious contest for the Labour crown by rowing in behind his rival.

Mr Burnham was given a hero's welcome by Labour MPs in the Commons on Monday, but in a well-timed heckle, a Tory MP warned them: 'He's not the Messiah!'

On Monday night, the former Greater Manchester mayor was scrambling to draw up a programme for government after Sir Keir set a timetable that could see him anointed as Prime Minister as early as July 17.

Opposition leaders questioned the right to govern of a man who was backed by just 25,000 voters in the Makerfield electorate – barely 0.05 per cent, or one-2,000th, of the electorate.

Nigel Farage called for an immediate general election, saying it was 'ridiculous to pretend that Andy Burnham has any kind of meaningful mandate to lead the country'. He added: 'If Labour thinks it can shove another professional politician into No 10, it has another thing coming.'

Kemi Badenoch said Labour was 'living in La La Land' if the party thought a change of leader would save it.

She said Sir Keir had failed the country over national security – and there should be an election 'if Andy Burnham is not able to set out how he's going to keep our country safe'.

The Tory leader accused Labour of plunging the country into chaos, saying: 'Britain is not being governed.' She added: 'We are living in serious times, yet the Government is paralysed and our country is in limbo.'

Allies of Mr Burnham were taken back by the short handover timetable set out by Sir Keir, having lobbied to take over in September after a summer of planning. Some believe the outgoing PM is trying to undermine his successor by denying him the time to prepare.

Some Labour MPs fear Mr Burnham has neither the team nor the detailed policy plans to start immediately.

One former minister said: 'If you can't choose between Ed Miliband and Wes Streeting as your Chancellor then you don't know what you're trying to do.'

On Monday night, Mr Burnham was holding talks with Labour backbenchers, many of whom he has never met.

On a dramatic day in Westminster:

• Sir Keir was moved to tears as he delivered his resignation speech on the steps of No 10 just days after vowing to fight on;
• Mr Burnham brushed aside calls to hold an early election, saying journalists asking the question were 'jumping several hurdles'; 
• Labour MPs opposed to a coronation were lobbying Sir Keir's right-hand man Darren Jones to stand; 
• The EU postponed a planned summit on Labour's Brexit reset next month to give Mr Burnham time to set out his position; 
• Mr Burnham faced growing pressure to abandon plans to appoint Mr Miliband as Chancellor, amid fears it could destabilise the financial markets; 
• The long-delayed Defence Investment Plan could be postponed again to give Mr Burnham time to assess his priorities on a subject on which he has been vague; 
• A snap YouGov poll found voters back Sir Keir's decision to quit by a margin of 62 per cent to 19 per cent. 

On Monday night Donald Trump described Sir Keir as a 'lovely man' and 'sort of a friend of mine'.

Mr Burnham has been on the march to Downing Street since his decisive victory over Reform in last week's Makerfield by-election.

In the immediate aftermath of the result, Sir Keir vowed to fight any contest. But in what may be his final U-turn, he dropped the plan following talks with his wife Victoria and his dwindling band of allies at Chequers over the weekend. 

Allies of Mr Burnham had warned they were ready to unleash a wave of ministerial resignations if the PM refused to quit.

As Lady Starmer and loyal staff and ministers looked on, Sir Keir said he was going because Labour MPs were asking who they want to lead them into the next election. He added: 'I have heard the answer of my parliamentary party to that question. And I accept that answer with good grace.'

Attorney General Lord Hermer, Sir Keir's closest friend in politics, claimed the PM was not angry.

But a senior Labour source said he was 'incandescent' about having to go.

The source revealed that he was so furious at Mr Miliband and Home Secretary Shabana Mahmood for telling him to set out a timetable for departure last month that he discussed sacking them, before being warned it could collapse the Government.

Mr Streeting's decision to throw his weight behind Mr Burnham saw him branded 'Coronation Streeting'.

The former health secretary, who quit the Cabinet last month to stand for the leadership, said he had spoken with Mr Burnham 'at length' and concluded the new Makerfield MP could 'win the fight of our lives against the forces of nationalism'.

The former Cabinet minister added: 'We could spend the summer exaggerating small differences, or we can roll up our sleeves and help him to deliver the change our party and our country needs.'

Mr Burnham paid tribute to Sir Keir and confirmed he will put his name forward to succeed him. He said the PM's resignation 'marks the beginning of a transition and it is important that this process is conducted in an orderly and responsible way'.

'I will put myself forward as part of this process,' he said. 'The country expects stability, seriousness and a continued focus on the issues that matter most and that is what it will get.'

If Mr Burnham avoids a leadership contest he will have the tiniest mandate in history to lead the country. He did not stand on Labour's manifesto at the last election.

And he will become the first prime minister in modern history not to have served either in one of the great offices of state or as Leader of the Opposition.

Yet he was greeted with cheers when, fresh from changing into a suit in a train toilet as he travelled down from Manchester, he arrived in the Commons to be sworn in. Westminster Hall was packed as MPs jostled for possible posts while Mr Burnham shook hands and took selfies.

Labour's decision to ditch Sir Keir shatters the party's manifesto pledge to 'stop the chaos' of the Tory years.

Under the timetable laid out by the PM, nominations for a Labour leader will open on July 9 and close a week later – on the day Parliament breaks for the summer recess. If Mr Burnham is the only candidate he could become prime minister the following day.