Barack Obama’s long-standing education secretary, Arne Duncan, will stand down from his role in December. 

Duncan, one of the last remaining members of the US president’s original cabinet, says in a message to staff that he will be returning to Chicago to live with his family. 

The politician is unsure what he will do next, but adds that he hopes his future will “continue to involve the work of expanding opportunity for children”.

Education department official John B King Jr is set to step in as acting secretary of the department through to the end of Obama’s term in 2017. 

“John comes to this role with a record of exceptional accomplishment as a lifelong educator - a teacher, a school leader, and a leader of school systems,” Duncan says in a letter to department officials obtained by the Associated Press.

Obama does not intend to nominate King or another education secretary during the rest of his presidency, a White House official said. 

As education secretary, Duncan prioritised K-12 education, and his first signature initiative was the Race to the Top programme, which involved states competing for federal grants. During his seven years in the role, Duncan repeatedly came into conflict with US teaching unions. 

Obama will discuss the change in the department at the White House later today.