Updated 8:41 a.m. ET Wednesday 6/5
(CNN) - Susan Rice, United States ambassador to the United Nations, will replace Tom Donilon as President Barack Obama's national security adviser, a senior administration official said Wednesday.
The president will announce the personnel change Wednesday afternoon at the White House, an administration official said.
Samantha Power, former special assistant to the president and senior director for multilateral affairs and human rights at the National Security Council, will take Rice's spot as U.S. ambassador, a senior administration official also said.
Rice, a longtime Obama confidante, became the center of controversy in the days after the attack on a U.S. diplomatic post in Benghazi, Libya, last year after she maintained the attack was a spontaneous act during a protest rather than the terror attack.
Republican Rep. Jason Chaffetz of Utah pounced on the staff change Wednesday morning, criticizing Rice for lacking the right judgment for the job.
Rice was considered a top contender to succeed Secretary of State Hillary Clinton at the start of Obama's second term, but Republican pushback forced her to withdraw from consideration in December.
Obama ultimately nominated former Sen. John Kerry for the post.
As the Chaffetz tweet indicates, Rice could face renewed political opposition from the GOP in her appointment. The Senate, however, does not have to confirm the president's nominee for national security adviser.
Sen. John McCain, one of Rice's most strident critics in the Benghazi aftermath, wrote Wednesday that he's not pleased with her new role but pledged to work with her nonetheless.
Power, on the other hand, will need approval from the Senate for the ambassadorship. Known as a big proponent for intervening in human rights cases, she was one of the loudest voices making the case to get involved in Libya's civil war.
Power also made headlines in March 2008 for resigning from her role as an adviser to Obama's presidential campaign after she called his then-Democratic opponent Hillary Clinton a "monster." Power later apologized to Clinton and the two have put it behind them.
More importantly, both Power and Rice will be dealing with issues like chemical weapons in Syria, unrest across the Middle East and Iran's suspected nuclear weapons program - meaning the attention surrounding their new positions - especially for Power - will be high.
Obama picked Donilon - then deputy national security adviser - to replace retired Marine Gen. Jim Jones for the post in October 2010. Donilon was heavily involved in the raid to kill Osama bin Laden in 2011.
Rice was considered a possible candidate for the job when Jones stepped down, as she was one of Obama's most public foreign policy voices during his 2008 presidential campaign.
Donilon also served as chief of staff to Secretary of State Warren Christopher in the Clinton administration.