Keir Starmer is plotting a blizzard of activity before the crunch by-election as he braces for a challenge by Andy Burnham. 

Downing Street has been lining up 'legacy' policies to improve the PM's standing with Labour MPs, including an under-16s social media ban.

This morning Sir Keir vowed legislation to stop children being able to send and receive nude images - unless tech firms act first.  

The critical Makerfield contest is entering its final 10 days, with Mr Burnham boasting that his campaign is 'on course'. 

A poll last week suggested he is 10 points ahead of his Reform rival, although the outcome could rest on whether Right-wing voters split to back the Restore candidate. 

Attention at Westminster is already turning to what Mr Burnham would do after his victory.

The Greater Manchester Mayor has made little secret of his intention to seek the Labour leadership, even though Sir Keir has been vowing to fight on.

However, there seems to be a divide among Mr Burnham's allies on the timing of any strike if he wins the by-election on June 18.

Some are urging the former Cabinet minister to seize the initiative immediately, while others say he should wait until he is reestablished at Westminster.

Sir Keir made it known over the weekend that he is determined to take on any challenge to his position.

Even if a contest is triggered the PM would be able to stand without needing to get 80 nominations from MPs - although many doubt he would want to go through the process of hustings. 

Former health secretary Wes Streeting has also indicated he wants to be a candidate.

In a speech at London Tech Week this morning, Sir Keir said: 'One issue is the ability for children with phones to send and receive nude images.

'For too long, people have been told that is simply the price of modern tech, that nothing can be done, that Government is powerless, that parents just have to accept it.

'I reject that completely, because tech should adapt to the needs of society, not the other way around.'

He added: 'That is why today I am calling on tech companies operating in this country to introduce device controls that prevent children from sending and receiving sexually explicit images.

'Because this is not an impossible challenge. These are some of the most innovative companies in the world and I believe they can solve it.

'But if they choose not to, then we will act and we will change the law because when it comes to the safety of our children, standing by is not an option.'

Labour MP Jess Phillips resigned as safeguarding minister at the Home Office earlier this year, accusing Sir Keir of being slow to threaten legislation on preventing children taking naked images of themselves, despite the technology being available.

Ms Phillips said this morning that she welcomed Sir Keir's announcement, saying tech firms could wipe out the issue 'overnight'.

In a video posted on social media last night, Mr Burnham said the 'warmth of reaction on the doorstep has been absolutely brilliant'.

'I may be getting a battering in the media but the campaign is on course,' he said.

'I'm fighting for every vote, I'm loving every minute.'

A Survation poll released on Thursday showed Mr Burnham with 49 per cent support in Makerfield, ahead of Mr Kenyon on 39 per cent.

The research put Rebecca Shepherd of Restore Britain on 8 per cent and Sarah Wakefield of the Green Party on 2 per cent, with the Liberal Democrats and Conservatives on 1 per cent.

The mayor's margin was bigger than suggested in an initial poll last month. 

However, constituency surveys are notoriously difficult to conduct, meaning there is a bigger margin for error than usual.