LONDON (AP) — A commission set up by to help improve the chances of Britain's poor has resigned, saying the government is too preoccupied with Brexit to build a fairer society.

The resignations are a blow to Prime Minister Theresa May, who has promised to tackle social injustice.

Since May took office in mid-2016, much of the government's time and energy has been consumed by divorce negotiations with the European Union.

Now, Labour ex-government minister Alan Milburn and his three fellow commissioners have quit the Social Mobility Commission.

In a resignation letter published Sunday, Milburn said the government "does not have the necessary bandwidth to ensure the rhetoric of healing social division is matched with the reality."

The government says Milburn's term in office has ended and he was due to be replaced.