Rishi Sunak hit out at the "forces that be" backing Tory leadership rival Liz Truss, as he positioned himself as the underdog in the race to replace Boris Johnson.

Mr Sunak used a speech in Grantham, the birthplace of Margaret Thatcher, to kick-start his campaign as he bids to win over Tory members.

Britain's Foreign Secretary Ms Truss, tipped as the favoured candidate among grassroots voters, today vowed to review all EU laws retained after Brexit by the end of next year in a "red tape bonfire" if she becomes prime minister, and to scrap or replace those that are deemed to hinder UK growth.

Ms Truss, a former Remainer turned ardent Brexiteer, is also the favoured candidate among the remaining Johnson loyalists in the party.

She said that if elected, she will set a "sunset" deadline for every piece of EU-derived business regulation and assess whether it stimulates domestic growth or investment by the end of 2023.

Industry experts would be tasked to create "better home-grown laws" to replace those that fail the test, if they are not ditched altogether.

Mr Sunak took aim at his rival's Brexit credentials in his speech this morning, which was heavy on warnings about the dangers of inflation and the need for a new "radicalism" in government.

Speaking to a mostly friendly crowd, he called himself the "underdog" but stopped short of naming Ms Truss personally.

He told the crowd: "The forces that be want this to be a coronation for the other candidate. But I think members want a choice and they are prepared to listen."

Pressed by reporters to be more specific, he said he was talking "generically".

Truss's enthusiasm sees her on course for No 10

Elsewhere in his speech, Mr Sunak sought to create a clear dividing line between himself and Ms Truss as he implicitly criticised her proposed tax cuts, which she says will help decrease inflation.

"If we are to deliver on the promise of Brexit, then we're going to need someone who actually understands Brexit, believes in Brexit, voted for Brexit," he told the crowd, to cheers.

In a speech punctuated by frequent applause, he also said: "We have to tell the truth about the cost of living.

"Rising inflation is the enemy that makes everyone poorer and puts at risk your homes and your savings. And we have to tell the truth about tax.

"I will not put money back in your pocket knowing that rising inflation will only whip it straight back out."

He called for the need for radicalism in politics, telling the crowd: "Real change is there, I swear it."

That change includes a promised plan to tackle NHS backlogs, driven in part by a so-called "vaccines-style" taskforce.

Warning against "privatisation by the back door", Mr Sunak announced plans to eliminate one-year NHS waiting times six months earlier than planned by September 2024, and to get overall numbers falling by next year.

It is a theme Mr Sunak focused on in an interview with The Times newspaper, where he said he would put the UK on a "crisis footing" from his first day as prime minister to deal with inflation and a host of other challenges.

"They're challenges that are staring us in the face and a business-as-usual mentality isn't going to cut it in dealing with them," he said. "So from day one of being in office I'm going to put us on a crisis footing."

The legacy and influence of Mrs Thatcher has overshadowed the Tory leadership campaign so far, with both candidates seemingly bidding to claim the mantle of the Tory grandee.

Mr Sunak laughed when pressed on whether the choice of location was a coincidence, telling reporters he believes what he is proposing is "common sense Thatcherism".

Deputy Prime Minister Dominic Raab, a supporter of Mr Sunak, said the former chancellor had set out a "credible" plan on the economy and on the NHS.

Liz Truss speaks to supporters during a visit to Marden in Kent today

Ms Truss is also on the campaign trail today and in an interview with the Telegraph, she robustly defended her economic vision.

Describing herself as an "insurgent" who wants to change things, she told the newspaper of her vision of the UK as a "high growth, high productivity, powerhouse".

On her plan to bring down inflation, she said: "I believe it is right that inflation will come down because inflation was caused by a global supply shock. But it was exacerbated by monetary policy. What I have said is in the future I'm going to look at the Bank of England's mandate. It is set by the Treasury. It was last set by Gordon Brown in 1997."

Pressed on her thinking on the Bank of England's mandate, she added: "What I want to do is look at best practice from central banks around the world, look at their mandates, and make sure we have a tight enough focus on the money supply and on inflation."