She is expected by bring her blunt negotiating style to her new, higher-profile post at a time when Russia and the United States are struggling find a political way out of Syria's conflict, one of the most intractable foreign policy challenges facing the Obama administration.
Rice, 48, also brings controversy to the position: She dropped out of the running to become secretary of state after Republicans heaped blame on her for the Obama administration's bungled account of the September 11, 2012, terrorist attack that killed four Americans at the US diplomatic post in Benghazi, Libya.
It's unclear whether Rice's appointment to the post signals a significant shift in Obama's foreign policy, particularly in Syria. Although Rice backed greater US involvement in Libya, administration officials have made clear they don't draw direct comparisons between the situation in Syria and the push to oust Libyan leader Muammar Gaddafi.
Obama plans to announce today that Rice will replace Tom Donilon as his national security adviser in July, a job that does not require Senate confirmation, according to a White House official speaking on condition of anonymity ahead of the announcement.
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Rice aggressively spearheaded Obama's foreign policy during her 4 and a half years as his top UN diplomat, promoting democracy in the Middle East and toughening sanctions against Iran and North Korea.
She gained a reputation for being blunt, sidestepping the niceties and courtesies that are a hallmark of diplomatic discourse when she deems necessary to make a point. She has sparred repeatedly with Russia's UN Ambassador Vitaly Churkin, who can be equally blunt. In private, Rice is known for her good sense of humour, which she displayed a few years ago at the UN Correspondents Association's annual awards gala.