Theresa May remains "fully committed" to reforming the National Insurance for the self-employed, Downing Street has said, despite a revolt from Tory backbenchers.
The Prime Minister has promised to listen to the concerns raised by Conservative MPs over a National Insurance hike announced in the Budget.
As she addressed the row during a press conference in Brussels, Mrs May backed the changes introduced by Philip Hammond but said there would be no vote until the autumn.
She (Munich: SOQ.MU - news) pledged that the embattled Chancellor would speak to MPs (BSE: MPSLTD.BO - news) about their concerns and publish a paper explaining the proposals before they are introduced.
A review of modern employment practices by RSA chief executive Matthew Taylor is due over the summer.
The Government paper is expected to include proposals to extend benefits such as parental leave to the self-employed.
"The Prime Minister has said that the Chancellor and his ministers will be talking to MPs and businesses over the summer," Mrs May's spokesman said. "The Prime Minister talks to MPs all the time."
Under the measure, Class 4 National Insurance contributions, which are paid by those with profits of £8,060 or more a year, will rise by 1% to 10% in 2018, with a further 1% increase in 2019.
The spokesman said the paper would spell out changes to the self-employed but also what new rights they might get.
"We are bringing forward legislation in the autumn in reference to the National Insurance announcements which were made in the Budget," he said.
Labour has claimed the Prime Minister - who with her comments in Brussels effectively put the brakes on the Chancellor's Budget proposals - had made a "partial U-turn".
But Mrs May said the proposals would make National Insurance "simpler, fairer and more progressive".
The Prime Minister also said the shift towards self-employment was "eroding the tax base" and making it harder to pay for public services "on which ordinary working families depend".
Responding to Mrs May's move to leave the door open to more concessions to her rebel MPs, shadow chancellor John McDonnell called on her to show leadership and scrap the proposals.
"The fact the Prime Minister won't fully support her own Chancellor's Budget measure, and has been forced by Labour to row back on it just 24 hours after he delivered his speech in Parliament, shows the level of disarray that exists at the top of Government," he said.
"What is even more alarming is that the Government didn't stop and think before announcing such a tax hike."
The rebellion by Tory backbenchers over the changes has grown to about 20 MPs.
Conservative MPs and the Government's opponents angrily pointed to a manifesto pledge on tax and National Insurance given by David Cameron during the 2015 general election campaign.
Dissent is not just confined to backbenchers. Welsh Office junior minister Guto Bebb could be facing the sack for declaring in a radio interview: "I think we should apologise."
And he added: "I will apologise to every voter in Wales that read the Conservative manifesto in the 2015 election."
Mr Hammond insisted that with Brexit the circumstances had changed since the 2015 manifesto.
His proposal won the backing of the Institute of Fiscal Studies in its analysis of his Budget measure