President Obama named Susan Rice as his national security adviser on Wednesday, despite persistent criticism from Republicans over her initial account of the Benghazi terror attack.

Obama, speaking in the Rose Garden, called Rice a "tireless advocate" for advancing America's interests.

"She is at once passionate and pragmatic," Obama said.

Rice will replace Tom Donilon, who is resigning from the post. Rice, the current U.S. ambassador to the United Nations, does not need Senate confirmation for the job.

The ambassador had earlier been considered in the running for the secretary of State post, which does require confirmation, but withdrew from consideration amid the continuing fallout over her role following the Benghazi attack.

Rice went on five Sunday shows after the attack and claimed it was triggered by protests over an anti-Islam film, an explanation many lawmakers said at the time was inaccurate. The administration later acknowledged there were no protests on the ground in Benghazi, though they have not officially ruled out that protests elsewhere may have played a role.

Republicans bristled at the news that Rice was being named to the new position. Sen. Rand Paul, R-Ky., accused her of "misleading" the public on Benghazi.

"How are they going to have the authority for people to believe what they're saying, when he's promoting someone who directly and deliberately misled the public over Benghazi?" Paul said on Fox News.

Rice's defenders dispute that charge.

The administration, under pressure from the media and Republicans, last month released the so-called "talking points" which showed officials drafting and re-drafting their storyline in advance of Rice's appearance. The intelligence community did cite demonstrations -- however, references to militant and Islamic extremist groups, and to prior security warnings and incidents, were ultimately stripped out after objections from various administration officials.

It's unclear what level of involvement Rice had in this process. Officials, speaking in her defense, have said she was merely citing the assessment she was given on Sept. 16.

Former Obama aide Samantha Power, meanwhile, was nominated to succeed Rice as U.S. ambassador to the U.N. Power was an aide to the Obama campaign in 2008 but resigned after a report was published in which she called then-candidate Hillary Clinton a "monster."

A senior official told Fox News that Donilon decided to leave the security adviser post after his wife took a job that involves a lot of foreign travel. He has been in the administration since the start, first as deputy national security adviser.

Fox News' Ed Henry contributed to this report.