Sir Robert Buckland has become the first cabinet minister to publicly switch sides in the Conservative leadership contest.

The South Swindon MP was backing Rishi Sunak citing his ability to lead the country through “challenging economic times” but has now publicly come out in support of Liz Truss. 

In an article for The Daily Telegraph, the newly-installed Welsh Secretary said he now believed that Ms Truss’s economic proposals offered the best prospect of getting through the current crisis.

“Her plans give us our best shot at reaching our potential with the high-growth, high-productivity economy that we need not only to get us out of this crisis but to protect ourselves from the next,” he wrote.

Sir Robert’s defection will come as another blow for Mr Sunak, the former chancellor, who has sought to stress his willingness to tell difficult truths while accusing his rival of peddling “fairytale” economics.

It will also reaffirm Ms Truss’s status as the clear frontrunner, with MPs hoping for a ministerial job in the new government looking to rally to the likely winner.

Earlier this week, former minister Chris Skidmore became the first MP to declare he was swapping his allegiance and backing Ms Truss.

In his article, Sir Robert said it was not easy changing sides mid-campaign but that he believed it was the right thing to do.

“As the campaign has moved on, and as I have listened carefully to both candidates, I have thought deeply about the issues that move me and what I want to see the next prime minister doing,” he said.

“Changing your mind on an issue like this is not an easy thing to do, but I have decided that Liz Truss is the right person to take our country forward.”

North Swindon MP Justin Tomlinson had initially backed leadership hopeful Kemi Badenoch, but she didn't make the final two. 

One of Liz Truss or Rishi Sunak will be the next Prime Minister of England after beating out their rivals, like Penny Mordaunt and Tom Tugendhat. 

A decision on which one it will be is expected to be made on September 5, with the two candidates carrying out a series of debates in the meantime. 

This will all triggered by Boris Johnson's resignation earlier this year, with the former London Mayor unable to shake off growing pressure to do from his Tory colleagues.