Downing Street has approached some of Britain's biggest companies asking them to give public support for the Government's approach to Brexit.
Executives have been asked to sign a joint letter declaring they wish to "make a success of Brexit" and welcome the Government's commitment to negotiating a transition period to avoid a cliff-edge withdrawal from the EU.
But the approach was not welcomed by some of those approached, with one executive reportedly saying: "There is no way we could sign this given the current state of chaos surrounding the talks."
It is understood the letter, obtained by Sky News, was drafted by Number 10 and was due to be made public as Theresa May seeks to build a consensus around the withdrawal legislation going through Parliament.
No date is yet thought to have been fixed for its publication.
The leaked text says that signatories will include "leaders of some of the UK's most dynamic businesses operating in sectors as diverse as technology, financial services and advanced manufacturing", including supporters of both the Leave and Remain sides in last year's referendum.
"Fifteen months later, we all share an understanding that Brexit is happening, a commitment to ensure that we make a success of the outcome for the whole country, and a confidence that a global Britain has the potential to become one of the most productive economies of the 21st century," the text read.
"This month the Government's Repeal Bill will initiate a programme of legislation that will make Britain ready for life outside the EU.
"We believe this is a good time for employers to work with Government and Parliament to make a success of Brexit and secure a bright future for our country."
The letter states that signatories welcome the Government's commitment to negotiating an interim period after the formal date of Brexit in 2019 to give firms time to adapt to the changing relationship with the EU.
It says that businesses with existing trade links with countries like the US, India, Japan and Mexico should "stand ready to use their expertise and networks to cement future relationships" as the UK seeks new partners outside the EU.
"As business leaders, we have a duty to our shareholders and employees to continue to grow our businesses and ensure that they remain strong," the letter said.
"As part of this we are also determined to see the UK continue to be a prosperous and united force for good in the world and are ready to play our full part to achieve this as Britain leaves the European Union."
Downing Street said it did not comment on leaked letters.
The Prime Minister's official spokesman there has been a "lot of engagement between No 10 and business", including a meeting Mrs May hosted in the Cabinet room.
"Business has an important voice in the conversation that's taking place over Brexit and we will make sure we continue to listen to them," said the spokesman.
"If you look at the investment that continues to take place in the UK economy since Brexit it is clear there is business confidence, significant investment from abroad and at home we continue to have record levels of employment."
Labour MP Ben Bradshaw, a leading supporter of the Open Britain campaign, said: "It's little wonder the Government's letter-writing campaign has leaked when the voices of British business are so opposed to their hard Brexit plan.
"Just today, businesses in sectors ranging from farming to hospitality have reacted with fury to the Government's leaked plans to damage our economy by carrying out a draconian crackdown on immigration from the EU.
"And UK businesses have been clear that they value our trade links with the European Union, and that leaving the single market and customs union will risk damaging our economy."
Liberal Democrat leader Sir Vince Cable said: "It's interesting the Government want to start a letter-signing competition on this.
"I rather suspect the number of businesses wanting to remain in the single market and customs union far exceed those gagging to leave it.
"It's already becoming clear that their so-called transitional arrangement, designed to appease the business community, is not going to work.
"The Government has unwisely made a unilateral commitment to break the rules around freedom of movement and in doing so, won't be able to secure the agreement of the EU on transitional trading arrangements.
"Rather than wasting their time touting for signatures, the Government should be concentrating on making swift and concrete progress in these vital Brexit negotiations.
"As it stands, the UK risks crashing out of the EU without any deal at all, with disastrous consequences for our economy."