The Institute of Economic Affairs' trade policy chief has offered up advice on negotiating Brexit to the Conservative leadership hopefuls.
Shanker Singham, who was dubbed the "brains of Brexit" for his role in creating a Chequers deal alternative, said it was "critical" not to rule out a no deal.
"No one party can say it is going to take no deal off the table, it is not possible to do that," he told talkRADIO's Ian Collins.
"As everybody who has negotiated anything knows, it is pretty critical that you don't tell the person on the other side of the table that you will take whatever deal they are prepared to give you."
Mr Singham's Brexit report, entitled 'PLAN A+ Creating a prosperous post-Brexit U.K' was championed by politicians including Jacob Rees-Mogg, David Davis and Boris Johnson, and was billed as an alternative to Theresa May's Chequers deal until it was withdrawn following criticism from the Charity Commission.
In a written warning to the IEA, the charity watchdog said the report presented just "one proposal for the way that Brexit should be achieved".
However, the IEA are currently in the process of contesting the official warning.
Mr Singham continued: "This is not about choosing no deal, or not choosing no deal.
"My advice to whoever emerges from this process of the leadership contest in the Conservative Party would be a significant amount of the Withdrawal Agreement as is currently there is doable, workable."
According to Mr Singham, the "first step" is to tell the EU what the country "actually needs", as well as considering "what will get through the Commons" in a meaningful vote.
He added: "There are some things that we would need that are different from the current Withdrawal Agreement and my advice would be to go and negotiate those."