A possible challenger has emerged who could put British Prime Minister Sir Keir Starmer out of a job before the northern summer as his government faces internal turmoil.

The Times newspaper reports that Health Minister Wes Streeting, arguably Starmer’s best-positioned rival, was poised to resign and fire the starting gun on a leadership contest.

The news came as the King delivered a ceremonial speech at the opening of parliament in Westminster on Wednesday (local time), forcing both sides of politics to pause.

Starmer ​has tried to brush off the challenges to his authority and the King’s speech — written by the government and delivered by the monarch — announced plans to boost economic growth, energy security and defence.

Opposition Leader Kemi Badenoch said it was “absolutely preposterous” that the government was laying out its agenda while its ministers were resigning and “a large proportion of the party is saying that the Prime Minister needs to go”.

A direct challenge from Streeting would signal a deeper crisis for Starmer. It could trigger a new leadership contest if the health minister has the support of 81 Labour MPs to launch a bid.

Earlier, Streeting briefly met Starmer at the Prime Minister’s Downing Street office.

But Streeting’s team said he would not comment on that meeting to ensure he didn’t distract ‌from the King’s Speech.

Starmer has weathered days of growing calls to quit after Labour suffered heavy losses in local and regional elections. He was looking to the King’s address to reassert his authority and “get on with the job of changing our country for the better”.

But what had ‌already promised to ‌be a difficult ⁠day, in which Starmer would be forced to mingle in front of television cameras ​with opponents who had delighted in his woes, took a turn for the worse in the morning.

A defiant Prime Minister Keir Starmer has told ministers he’s getting on with governing. Photo: AAP

News of the challenge broke as the King, dressed in full ceremonial military dress and accompanied by ⁠the Queen, was approaching parliament in his horse-drawn royal ‌carriage.

Minutes later, ‌Starmer led a procession of MPs from one chamber of parliament, the House of Commons, to another, the House ​of Lords, part of the complex, centuries-old ritual of reopening the legislature that takes place roughly every year.

As the King’s representative knocked loudly on the heavy door, one MP joked, “Not now, Andy”, in reference to ​Andy Burnham, ​another possible challenger. He is mayor ​of Greater Manchester and thus wasn’t entitled to take part ‌in the ceremony.

Television footage showed Starmer making stiff small talk with Badenoch, who on Tuesday had posted on social media that he would be lucky to survive two weeks in his job, let alone two years.

The MPs in Starmer’s own party — almost a quarter of whom want him to quit — followed ​behind.

The King then read out a speech written by Starmer’s government, setting out their plans for the next ​12 months.

“I pray that the blessing of Almighty God may rest upon your ​counsels,” he finished.

-with AAP