David Lidington, the Cabinet Office minister brought in to replace disgraced Damian Green in Mrs May’s January reshuffle, said Britain may want to reconsider in “10 or 20 years’ time”.
He told the Telegraph that the question of returning to the fold in a reformed EU would be “something for future generations to consider”.
This week, former education secretary Justine Greening suggested MPs would be able to “undo” Brexit if it did not “work for them”.
French president Emmanuel Macron said the UK could be welcomed back into a “reformed and simplified EU” within a few years.
Asked whether they could be right, Mr Lidington said he did not believe Britain could rejoin the bloc in its current form.
However, he said: “We may be looking in a generation’s time at an EU that is configured differently from what it is today.
“The exact nature of the relationship between the United Kingdom and that future system, whatever it turns out to be, of European cooperation is something that future parliaments, future generations will have to consider.”
The Cabinet Office minister also revealed he found it plausible that Britain could rejoin a customs union with the EU after leaving the bloc.
Although the government has vowed it will leave the single market and the European customs union by March 2019, Mr Lidington said if if there was “some different framework that we can arrive at in negotiations that will be mutually beneficial” it could work to “everybody’s advantage”.
Mr Lidington, who backed Remain in the 2016 referendum, said his views on Brexit have not changed, but he believes it is his job to implement the will of the people.
Following the prime minister’s reshuffle earlier this month, he is arguably the second most powerful politician in he country, after Theresa May.
His comments led some to question whether he is the right man for the job.
Mark Fox wrote on Twitter: “Theresa May and David Lidington are the wrong people to be heading a Brexit Government. Time for a proper reshuffle starting with the PM & deputy.”
While Max Gomila said: “The British people have voted to leave the EU including the single market and the customs union. Why won’t Mr Lidington respect the outcome of the referendum?”