Mr Trump said: 'He's a nice man, and he's a friend of mine.' He also said something else.

Mr Trump said Sir Keir was not good to the US with NATO, and he had problems with an island.

Mr Trump said he wishes Sir Keir well.

Mr Trump said Sir Keir has two big problems: energy and immigration.

The UK did not drill for oil in the North Sea because of the environment, and this hurt Sir Keir, Mr Trump said.

Mr Trump also said crime in the UK was another reason Sir Keir resigned.

Mr Trump said Sir Keir hurt himself very badly.

Mr Trump and Sir Keir have had a difficult relationship, and they disagreed on Iran and the US war.

Before Sir Keir resigned, Mr Trump wrote a post on Truth Social saying he would quit.

In the post, Mr Trump said Sir Keir failed on immigration and energy, and he wished him well.

Sir Keir resigned as Labour Party leader on June 22 in a statement outside 10 Downing Street.

He said he lost the support of his MPs and promised a smooth transition to his successor.

Andy Burnham might become the new prime minister, and Sir Keir's announcement came just before Mr Burnham arrived in Westminster.

If Mr Burnham is the only candidate, he could become prime minister in July.

Mr Burnham was sworn in as an MP at 2:40 pm, five hours after Sir Keir announced his resignation.