RISHI Sunak has promised to tell the truth if he becomes the next prime minister, with a swipe at the economic policies of his rivals. 

“It is not credible to promise lots more spending and lower taxes,” he told colleagues at his campaign launch in Westminster. 

Tax has been one of the central issues of the contest so far, with nearly all of the candidates promising to immediately reduce the tax rate and shrink the state.

Many have said they will cancel the planned increase in corporation tax due next April. 

However, Mr Sunak said there needed to be a “grown up conversation” about the economy. 

“My message to the [arty and the country is simple, I have a plan to steer our economy through these headwinds. We need a return to traditional Conservative economic values, and that means honesty, and responsibility, not fairy tales. 

“It is not credible to promise lots more spending and lower taxes.”

He promised that he would get the tax burden down, but only “once we have gripped inflation.”

“It is a question of when not if”. 

The Herald:

Mr Sunak used the phrase “grown up conversation” again as his speech came to an end. He would, he said, “tell you the truth.” 

“A better future is not a given, it is earned. That is why I am standing to be the next leader of the Conservative Party and your prime minister. “

Despite helping to topple the current Prime Minister with his unexpected resignation last week, he opened his speech by praising Boris Johnson saying he was “one of the most remarkable people I have ever met.” 

He added: “And whatever some commentators say, he has a good heart. 

“Did I disagree with him? Frequently. Is he flawed? Yes, and so are the rest of us. Was it no longer working? Yes, and that’s why I resigned. 

“Let me be clear, I will have no part in a rewriting of history that seems to demonise Boris, exaggerate his faults or deny his efforts.”

His campaign was given a boost as Grant Shapps pulled out of the race to back the former Chancellor. 

The Transport Secretary announced his decision to withdraw in a tweet. Mr Sunak, he said, had the “competence and experience to lead this country.”

Dominic Raab, the deputy Prime Minister, also made public his support for Mr Sunak. He told colleagues that his ex-cabinet colleague was best placed to stop a Labour government propped by the Lib Dems and the SNP. 

He said the “threat of the SNP breaking up the UK is real” and that there was “no time to learn on the job.”

However, two of Boris Johnson’s closest allies threw their weight behind Liz Truss. 

Nadine Dorries and Jacob Rees-Mogg said that despite the foreign secretary voting for Remain in 2016, she was a “stronger Brexiteer” than either of them. 

Asked if she was the “stop Rishi” candidate, Mr Rees-Mogg said: “Liz Truss is the best candidate. She’s a proper Eurosceptic. She will deliver for the voters. She’ll deliver for the voters. She believes in low taxation.”

Ms Dorries added: “And she’s a woman.”

Mr Rees-Mogg said Ms Truss had been his strongest supporter in the Cabinet in terms of seeking Brexit opportunities. He added: “When we discussed taxation, Liz was always opposed to Rishi’s higher taxes. That again is proper Conservatism. And I think she’s got the character to lead the party and the nation.”

Their support is being seen as a tacit backing for Ms Truss from the Prime Minister, who reportedly blames Mr Sunak for his downfall.

During his campaign launch, Mr Sunak was forced to deny rumours that he was being aided by Dominic Cummings, the former chief aide to Mr Johnson, who is now one of his biggest critics.