London, United Kingdom CNN  — 

At least 60 British business leaders have signed a letter calling for a public vote on the country’s Brexit deal, amid growing concerns that the United Kingdom will exit the European Union in March without an agreement.

Dozens of business heavyweights – including Waterstones book store managing director James Daunt, and Wahaca restaurant co-founder Mark Selby – signed the letter published in the Sunday Times, calling for a “People’s Vote” on Brexit.

They said the proposals being discussed by the government and the European Commission were “not nearly as good as the current deal we have inside the EU.”

“The uncertainty over the past two years has already led to a slump in investment, which will make our country poorer,” said the letter.

It also warned that the country was facing either “a blindfold or a destructive hard Brexit,” adding that the “ultimate choice should be handed back to the public with a People’s Vote.”

The letter did not specifically mention a second Brexit referendum.

The People’s Vote is a grassroots campaign calling for a public vote on the UK’s exit deal with the EU.

The British public voted in a June 2016 referendum to leave the European Union by a margin of nearly 52% to just over 48%.

PM: ‘The people have already voted’

Last month, hundreds of thousands of demonstrators marched through central London – in what was was dubbed the People’s Vote March for the Future – demanding a referendum on the terms of Britain’s exit from the EU.

But opponents of a public vote on the final Brexit deal say the proposal is undemocratic because the British people have already had their say.

Both Prime Minister Theresa May – who campaigned for the UK to remain in the EU – and Labour Party leader Jeremy Corbyn have said the original result should be respected and fear punishment at the ballot box by so-called Leave voters if they don’t.

Whatever agreement is reached by the UK government will be subject to approval by Parliament, where May’s Conservative Party remains deeply divided over Brexit and relies on Northern Ireland’s Democratic Unionist Party for a majority. The deal will also have to be ratified by the parliaments of the remaining 27 EU nations.

The original plan is for a 21-month transition period starting March 30, 2019, as soon as the UK has left the EU.

But with the two sides failing to come to an agreement on how the new relationship will work, May last month proposed extending this arrangement “for a few months.”

With time running out, the fear is the UK could crash out of the EU with no deal on vitally important issues like tariffs and trade.