President Obama’s national security adviser Tom Donilon will resign from his post and be replaced by Ambassador Susan Rice, a White House official confirmed to The Hill.
President Obama will make the announcement at 2:15 p.m. on Wednesday.
Donilon will step down from his post in July.
Since Obama took office, Donilon has served as a primary adviser to the president on counterterrorism policy and the wars in Iraq and Afghanistan. He served for more than four years as Obama's national security adviser.
Recent reports though painted a picture of an adviser often in conflict with other administration officials.
A profile in Foreign Policy magazine reported that Donilon had a tense relationship with White House Chief of Staff Denis McDonough. The national security adviser denied any rift between him and McDonough.
"It pains me to think anybody would think he's leaving because of me," McDonough said in an interview with The New York Times, which first reported the news of the staff shakeup.
Rice's relationship with Republicans has been troubled because of the controversy surrounding the terrorist attack last Sept. 11 on the U.S. Consulate in Benghazi, Libya.
Days after the incident, Rice blamed the assault on the actions of a mob riled up by an anti-Islam film. The White House later acknowledged it was a planned terror attack, and internal administration emails released over the past months showed officials debating over references to terrorism in talking points Rice used for her interviews.
Republicans have questioned if the administration sought to play down the terrorist angle for political gain months before the election.
Republicans on Wednesday said they would try to work with Rice.
In a message on Twitter, Sen. John McCain (R-Ariz.) said he disagreed with Rice's appointment but would make a "every effort" to work with her.
Sen. Bob Corker (Tenn.), the ranking Republican on the Senate Foreign Relations Committee, made a similar statement about Rice.
"I appreciate the work Tom Donilon has done as National Security Advisor," Corker said in a statement. "Now that the president has made a decision on his replacement, I had a very good conversation with Ambassador Susan Rice to let her know I look forward to working with her on shaping important foreign policy and national security issues as she serves in her new role."
Rice was widely seen as Obama’s top choice to replace former Secretary of State Hillary Clinton. But amid the Benghazi controversy, Rice withdrew her name from consideration and Obama nominated Sen. John Kerry (D-Mass.), who was confirmed to the post.
Rice’s selection as national security adviser does not require her to be confirmed by the Senate.
Power also served as a foreign policy adviser for Obama’s first presidential campaign, where she drew controversy after referring to primary rival Hillary Clinton as a “monster” in an interview with The Scotsman newspaper.
Power subsequently apologized for the comments, later resigning from the campaign.
She eventually rejoined the Obama administration, where she worked alongside Clinton.
Power stepped down from her most recent post in the White House in February. She has been considered the favorite to replace Rice.
This story was posted at 7:13 a.m. and last updated at 9:58 a.m.