Sharon Graham, general secretary of Unite union, told the BBC’s Today programme she hoped the government was not “looking to water down” the Employment Rights Bill because “they made a promise to the British people… that they would make work pay”.

“The mood music wasn’t looking too good and what I do hope is that they don’t intend on now slowing this down or indeed scrapping some parts of it altogether.”

Graham accused ministers of “saying different things” to union officials and businesses.

But Luke Johnson, director of bakery chain Gail’s, claimed “every single major business or employer organisation opposes this bill”.

He highlighted that so-called “day one rights”, which will give more power to workers to claim unfair dismissal against their employer and request flexible working, would “just discourage people from investing from taking on new workers and from creating jobs”.

“I think you should not allow full employment rights including flexible working and so forth from day one, I think there should be a probationary period of two years which is the current system.

“If you increase the cost of employing people, you will increase the prices of things in the High Street,” he added.

The TUC, the umbrella group for trade unions in the UK, urged the government to “stay on course” in delivering the bill.

Its general secretary Paul Nowak told the BBC: “I am confident that the government will deliver on its commitments to enact that Employment Rights Bill in full.”

Concern is coming from unions on the right of the trade union movement, not the usual suspects who might be expected to criticise the government.

Nowak said the bill “will give a massive boost to rights for millions of working people in this country, lots of whom are in insecure, low-paid employment” and he urged the government to “stay on course” to deliver the bill in full.

He also pushed back on the idea the government could make concessions to business in the legislation.

“Having people in well-paid, secure employment is good for everybody. It’s good for workers, but it’s also good for the good employers who are being undercut by the cowboys, and it’s good for the UK economy,” he added.

The Usdaw union represents more than 300,000 workers, many of whom work in supermarkets, factories and warehouses.

The union is concerned that an amendment to the Employment Rights Bill, which was added by the House of Lords in July, could be adopted by the government.

The amendment seeks to change the bill from a requirement for an employer to offer guaranteed hours to a right to request guaranteed hours by an employee.

The union fears this would be a weakening of their members’ rights because there would no longer be a right to a contract that reflects their normal hours of work.

The Federation of Small Businesses (FSB) has told the BBC that Angela Rayner’s resignation and the government reshuffle present an opportunity to “fix the issues” with the Employment Rights Bill.

“In some of our recent polling of members, 92% of employers said they were worried about this legislation. We have never got to that level in a poll,” said Craig Beaumont, director of policy at the FSB.

“They are overwhelmed by the changes that are coming. They don’t have HR teams. All these different measures scare them, and this is a chance to fix the issues.”

He said that Rayner’s resignation and the sacking of Employment Minister Madders – two key government supporters of the bill – could allow for some compromise.