President Obama on Wednesday named United Nations Ambassador Susan Rice as his next national security adviser, picking a fight with congressional Republicans who blocked her bid to lead the State Department after claiming she misled the public about the Sept. 11 terrorist attack on the U.S. mission in Benghazi, Libya.

In tapping Rice to replace outgoing National Security Adviser Tom Donilon, Obama is poking his finger in the eye of congressional Republicans, making a defiant pick that GOP leaders can do nothing to stop since the appointment does not require Senate confirmation.

"She is at once passionate and pragmatic," Obama said of Rice in a Rose Garden ceremony. "I think everybody understands Susan is a fierce champion for justice and human dignity, but she's also mindful that we have to exercise our power wisely and deliberately."

Obama also picked human rights activist Samantha Power, a first-term member of the president's National Security Council, to replace Rice. That nomination must be confirmed by the Senate.

But it's Rice who has been targeted by Republican lawmakers after claiming that the violence in Benghazi was a spontaneous reaction by protesters angered by an anti-Muslim video. Republicans are still upset that administration officials purposely omitted any reference to terrorism from Rice's talking points.

"Judgment is key to national security matters," said Rep. Jason Chaffetz, R-Utah. "That alone should disqualify Susan Rice from her appointment."

Rice was the leading contender to replace former Secretary of State Hillary Clinton but withdrew from consideration amid the GOP backlash over Benghazi.

Rice's new assignment is viewed as a consolation prize after being denied the nation's top diplomatic post. And though Obama will avoid another confirmation battle over Rice, this latest appointment gives Republicans a fresh opportunity to focus on the administration's handling of the Benghazi terrorist attack at a time when attention on the attacks has faded.

After it became known that the Internal Revenue Service was targeting conservative groups and that the Justice Department was secretly spying on journalists, Republicans turned their attention away from Benghazi. Rice's appointment, however, could renew calls from conservatives to determine why the administration bungled its handling of Benghazi and its response to the deaths of four Americans, including the ambassador.

"It demonstrates a tin ear on the genuine concerns on the tragedy of Benghazi," said Matt Schlapp, former President George W. Bush's political director. "When you take somebody who was at the center of the public relations strategy around Benghazi and give her a promotion, it seems to indicate you haven't learned any lessons."

When asked whether the White House feared that Rice's selection would stoke further debate about Benghazi, Obama spokesman Jay Carney emphatically replied, "Not at all." And Sens. John McCain, R-Ariz., and Lindsey Graham, R-S.C., two of Rice's most vocal critics, had surprisingly muted responses to her appointment.

However, political vulnerabilities remain for the White House. A new NBC/Wall Street Journal poll found that 58 percent of Americans believe the Obama administration's response to Benghazi raised doubts about the White House's integrity. And 41 percent said Obama was either totally or chiefly responsible for the mishaps.