Ms Rayner and Mr Reynolds have held a series of joint meetings with chief executives, unions and lobby groups meant to reassure them and explain the extent of the reforms and how they will work.

However, executives have repeatedly voiced their concerns. A survey by the Confederation of British Industry (CBI) of its members, which include AstraZeneca, Drax and PwC, found 62pc believed Britain was becoming a less attractive place to do business and invest. Looming jobs market reforms were the most common reason given.

An economic confidence index produced by the Institute of Directors (IoD), which is sometimes nicknamed the bosses’ union, plunged from a three-year high of +7 in July to -12 in August. The IoD cited “newsflow in recent weeks on employment rights” as one of the reasons for the slump.

Business leaders are concerned that the proposals as they stand would trigger a wave of costly and time consuming unfair dismissal claims. 

This will be a crunch week for discussions about the reforms as the Government gets closer to unveiling its employment rights bill next month. Ministers have promised to put forward the bill within the first 100 days of entering office.  

Sources said it was “unclear” if an agreement on day one workers’ rights will be reached in time for the bill, with fears in Whitehall that vague plans will “really worry people”.

“Everyone is trying to get to an agreement so that they can consult on something quite clear,” a Whitehall source said. 

“Getting [Chancellor] Rachel Reeves, Jonathan [Reynolds] and Angela [Rayner] in the same place will be the point at which we can close it off.”

A government spokesman said: “Our number one priority is economic growth and wealth creation which is why our plan for better workers’ rights is designed to help people into secure work and lead to a more productive workforce.

“This is why we are working in close partnership with business and civil society to find the balance between improving workers’ rights while supporting the brilliant businesses that pay people’s wages.”