Tony Blair has argued that EU leaders are willing to be flexible on freedom of movement of people to "accommodate" the UK after Brexit.
The former Prime Minister said his discussions with European leaders revealed they were prepared to "consider changes" around free movement, which is one of the key principles of membership of the Single Market.
Whether the UK leaves or remains in the Single Market has been hotly debated.
In an article published on the Tony Blair Institute for Global Change today, Blair said:
"The French and Germans share some of the British worries, notably around immigration, and would compromise on freedom of movement."
Blair suggested the "will of the British people" on Brexit may be changing, and leaders should "at least lead a proper debate about the options before us".
"Rational consideration of the options would sensibly include the option of negotiating for Britain to stay within a Europe itself prepared to reform and meet us half way," he said.
"Reform is now on Europe's agenda. The European leaders, certainly from my discussions, are willing to consider changes to accommodate Britain, including around freedom of movement.
"Yet this option is excluded."
Blair, who resigned in mid-2007 after 10 years in Downing Street, has previously said Brexit has given him a "direct motivation" to return to politics.