Keir Starmer and Rachel Reeves are set to tack hard to the left in the budget to buy themselves time and prevent an attempted leadership coup by backbenchers.The Independent has been told that the chancellor will bow to pressure scrapping the two child benefit cap altogether and unveiling a series of wealth taxes to fill the spending black hole in her budget.Backbenchers and senior party members have been assured that the tax raid will include a mansion tax on properties worth more than £2 million, a profits tax on gambling companies demanded by former PM Gordon Brown, and a levy on bank profits.Added to that transport secretary Heidi Alexander refused end speculation that fuel duty could rise for the first time in 15 years and electric cars will be subject to a new pay by the mile tax.Chancellor Rachel Reeves is finally set to unveil her budget after months of speculationThe minister was challenged on the issues on Sunday morning by Sir Trevor Phillips on Sky News and Laura Kuenssberg on the BBC.Ms Alexander pointed out that the government is freezing rail fares but after being asked three times about fuel duty, she said: “You would not expect me to speculate on what is going to be contained in the budget next week.”It is also being briefed that Ms Reeves will raise capital gains tax but will fall short of equalising it with income tax levels.A minister told The Independent: “The ink definitely won’t dry on this budget until Tuesday night but it looks like the PLP [parliamentary Labour Party] is getting what it wants…wealth taxes and an end to the child benefit cap.”The contents of the budget now though are being tied to the future of Sir Keir and Ms Reeves with continuing speculation that the PM could be ousted following a Downing Street briefing accusing Wes Streeting of plotting to replace him.Along with Mr Streeting, former deputy prime minister Angela Rayner, energy secretary Ed Miliband and home secretary Shabana Mahmood have been the centre of leadership speculation in the last fortnight.A senior party source told The Independent: “The PM and chancellor are buying themselves time. There will be elements of the media who hate these taxes but it will please members and the PLP.”It has also emerged that the decision to ditch an income tax rise breaking the manifesto commitment also came after pressure from backbenchers.One Labour MP said: “The message went up that it is hard enough for us to get a hearing on the doorstep as it is but if we did that [raise income tax], then the doors would have been closed on us and not reopened.“People would have just said ‘you lied, we can never trust you again.’”Health Secretary Wes Streeting was accused of trying to orchestrate a leadership coup (PA) More