Reforms of income tax and vehicle tax will come under further scrutiny this week, to the embarrassment of the Government, as backbenchers and opposition MPs push for significant amendments.

David Taylor, the Labour MP for Leicestershire North West, said that he had the backing of 17 MPs for an amendment demanding that Mr Brown should compensate the 1.1 million people left out of the Treasury's compensation package on the 10p tax reforms.

Mr Taylor said he believed it would cost the Treasury about £66million to compensate the remaining people damaged by the Government's plan to abolish the 10p starting rate of income tax. “We'd all like to see the end of it,” he told The Times last night. “It's only a small amount but to people that are hard up against it, it is not an insignificant figure.”

It also emerged that the Labour MPs Lynne Jones and Michael Meacher have separately tabled an amendment and an early day motion to push Mr Brown on the 10p tax issue. The mounting rebellion comes after the Treasury Select Committee, in a damning report last week, called on the Chancellor, Alistair Darling, to find the money needed to compensate those left behind.

Mr Brown and Mr Darling also face tough opposition to their plan to raise taxes for high-emission cars. Justine Greening, the Conservative MP for Putney, has tabled an amendment for the final stage of the Finance Bill to be debated this week, that will force the Government to drop plans to backdate the tax to 2001. Ms Greening told The Times: “You cannot introduce a tax to change people's behaviour when that behaviour was in the past. It is simply unfair. Families need to know now where they stand. They deserve that certainty.”

Several Labour MPs have also fiercely opposed the car tax changes, which are due to come into force in 2010. They argue that it is unfair for those on low incomes who cannot afford to upgrade their cars to more environmentally friendly models within the timeframe.

Martin Salter, one of the MPs who has led the rebellion, said last night that he had been given reassurances that Alistair Darling would look at the proposal again before its introduction next year. “I would like that assurance before the House rises for the summer recess,” he told The Times.

The Treasury has denied that it is preparing a U-turn. And Mr Darling does not have the spare £410 million needed to abolish the plan now.

Despite the fierce opposition, the Health Secretary, Alan Johnson, insisted yesterday that it had been a good year for Mr Brown.

He said: “In an analogy of Wimbledon, Gordon is not interested in strutting his stuff on the show courts; he is quite happy to do it on the outer courts, which makes him quite unique for a politician.”

There was also some support from the former Mayor of London Ken Livingstone, who said the party had to “hang in there and deliver”, not sack Mr Brown, if it was to have any chance of a fourth term.

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