Chancellor Jeremy Hunt is to speed up billions of pounds worth of tax and spending measures from his debt plan, announcing them a fortnight earlier than expected.
The Treasury will outline details of the plans later today, according to the BBC's Economics Editor Faisal Islam.
It is the latest of a series of U-turns on policies announced in the mini-budget.
The move is designed to help reassure jittery markets amid fresh claims that Prime Minister Liz Truss could be ousted by Tory rebels before the end of the month.
Truss fighting for her political future
Ms Truss will appeal to moderate Tory MPs to save her premiership tonight after it emerged that powerbrokers had held secret discussions about ousting her and arranging a “coronation”.
The Times reports that she will address the One Nation group of centrist Conservatives after a weekend in which three of her MPs called on her to quit and her new chancellor tore up the agenda on which she was elected only last month.
Senior members of the 1922 Committee of Conservative backbenchers held talks late on Friday evening about Truss’s future, The Times claims.
The discussion focused on the circumstances in which Sir Graham Brady, chairman of the committee, would have to tell Truss to stand aside, even though under present rules she cannot be challenged for 11 months.
Three Conservative MPs have publicly told Truss to resign. Crispin Blunt, a former minister, was followed by the backbenchers Andrew Bridgen and Jamie Wallis in demanding a new prime minister, in a sign that the appointment of Jeremy Hunt as chancellor has not quelled the rebellion against her leadership.
Who could replace her?
Media speculation is rife about who could replace the Prime Minister, if she is ousted.
Potential candidates include Rishi Sunak, this summer’s runner-up, and Penny Mordaunt, leader of the Commons.
Supporters of Ben Wallace, the defence secretary, who declined to stand last time, have approached MPs to canvass support. Jeremy Hunt is also being talked up after less than three days as chancellor.
This morning, Ms Mordaunt said: “Our country needs stability not a soap opera.”
Writing in The Daily Telegraph, she added: "The national mission though is clear, as the prime minister said. That is what we should all focus on now. It needs pragmatism and teamwork. It needs us to work with the prime minister and her new chancellor. It needs all of us.”
However, George Osborne, the former Tory chancellor, predicted that Ms Truss would be out by Christmas, telling Channel Four: “She is Pino, Prime Minister In Name Only, at the moment.”