Education Secretary Arne Duncan – one of the leading advocates of the controversial Common Core school standards and an architect of President Barack Obama's "Race to the Top" program  – will be leaving his post in December, the Associated Press first reported.

Obama is expected to make the formal announcement Friday afternoon.

AP Photo/Manuel Balce Ceneta

Duncan and Agriculture Secretary Tom Vilsack are the only members of Obama’s original cabinet from 2009.

Duncan has been known to make strong statements in defense of Common Core, once talking about why surburban moms oppose the standards.

“It’s fascinating to me that some of the pushback is coming from, sort of, white suburban moms who, all of a sudden, their child isn’t as brilliant as they thought they were and their school isn’t quite as good as they thought they were, and that’s pretty scary,” Duncan said in 2013. “You’ve bet your house and where you live and everything on, ‘My child’s going to be prepared.’ That can be a punch in the gut.”

Duncan was key to the Obama administration’s “Race to the Top” initiative that encouraged states to adopt Common Core or higher standards.

Over time, as the standards have become more contentious, Duncan sought to affirm that it would not lead to a de facto national curriculum and said that it wasn’t  necessary for states to adopt Common Core in order to receive “Race to the Top” federal grants.

Duncan’s department also called for ways help schools make children into “green citizens” regarding environmental matters.