Foreign secretary and Norfolk MP Liz Truss has become the 10th Conservative candidate to launch a campaign to succeed Boris Johnson as party leader and prime minister.

Ms Truss, who is the south west Norfok MP, has insisted she can be "trusted to deliver" and promised to reverse the controversial national insurance hike if made Tory leader.

The senior Cabinet minister, who is widely expected to be a front-runner in the already crowded race, has said she would “start cutting taxes from day one” to help with the cost of living.

Other contenders include former health secretaries Sajid Javid and Jeremy Hunt, ex-chancellor Rishi Sunak, his successor Nadhim Zahawi, transport secretary Grant Shapps, as well as trade minister Penny Mordaunt.

Former minister Kemi Badenoch and senior backbencher Tom Tugendhat have also thrown their hats into the ring.

Ms Truss’s pledge to scrap the national insurance rise, which came into effect in April, mirrors that of rival Mr Javid.

It marks a departure from her defence of the policy as a minister in Boris Johnson’s Cabinet, prior to his resignation, when she was bound by collective responsibility to support the move publicly.

The levy was introduced to raise funds for the NHS and social care, but has proved controversial at a time when households are feeling the squeeze from soaring food and energy bills.

Ms Truss argued “it isn’t right to be putting up taxes now”, and as leader she would take “immediate action” to assist with living costs.

She said she would “keep corporation tax competitive” – hinting that she wants to look again at Mr Sunak’s plans to hike the rate in April 2023, but did not go so far as to match some of her fellow contenders’ pledges to scrap the rise entirely.

The foreign secretary said she would “get the private sector growing faster than the public sector, with a long-term plan to bring down the size of the state and the tax burden”.

Writing in The Telegraph, she said: “Under my leadership, I would start cutting taxes from day one to take immediate action to help people deal with the cost of living.

“I would reverse the national insurance increase that came in during April, make sure we keep corporation tax competitive so we can attract business and investment into Britain, and put the Covid debt on a longer-term footing.”

Ms Truss said her plan would get the country back on track towards becoming a “high-growth and high-productivity powerhouse”.

“It is built on a clear and longstanding Conservative philosophy, including bold supply-side reform,” she added.

Ms Truss said she had “led the way” in making the most of Britain’s “new-found freedoms” outside the EU, but insisted “we can go further, whether it is doing more to champion innovation or charting our own course on regulation”.

She said she would bring “clear and decisive leadership” to Downing Street, adding: “Colleagues know I mean what I say and only make promises I can keep. I can be trusted to deliver.”

Ms Truss said the Tories can win the next election, but acknowledged it will be “an uphill battle”.