President Barack Obama‘s top national security adviser Tom Donilon is resigning and will be replaced by U.S. ambassador to the United Nations Susan Rice, marking a significant shakeup to the White House foreign policy team.

White House official confirmed the personnel changes Wednesday morning ahead of a planned announcement by the president later in the day.

Donilon has been a key foreign policy adviser to Obama since he first took office. But the 58-year-old had been expected to depart sometime this year, with Rice seen as the likely candidate to replace him.

Rice, a close Obama confidante, came under withering criticism from Republicans as part of the investigations into the deadly attack on a U.S. compound in Benghazi, Libya. Rice, relying on talking points from the intelligence community, said in television interviews that the attacks were likely spontaneous, which was later proven incorrect.