By Steve Holland and Susan Cornwell
WASHINGTON (Reuters) - Susan Rice is facing her first key test as President Barack Obama's national security adviser as she helps lead a White House effort to convince a skeptical Congress that the United States must respond to Syria's apparent use of chemical weapons.
Rice has made an abrupt transition from a high-profile and sometimes combative U.S. ambassador, who scolded the U.N. Security Council for failing to agree on Syria sanctions, to a behind-the-scenes power player at the White House.
Rice, who on Thursday evening moderated an unclassified phone briefing by top Obama security aides for congressional leaders, has had a patchy relationship with lawmakers.
She was pilloried by opposition Republicans for saying that a September 2012 attack on a U.S. diplomatic post in Benghazi, Libya, was the work of a spontaneous crowd rather than Islamist militants. Critics charged it was part of an attempt to protect Obama during his re-election campaign, which the White House vigorously disputed.
A November trip to Capitol Hill to smooth the waters did not go well, perhaps dooming her hopes to be Obama's second-term secretary of state.
But there are some signs that Rice, 48, who took over in early July as Obama's top security adviser, is building bridges to opponents and entertaining contrary views as the president weighs limited military strikes on Syrian military installations.
Republican Senators John McCain and Lindsey Graham, who opposed any move by Obama to nominate her for the State Department job, said they had nonetheless found a willing ear in Rice.
"As far as I'm concerned, she's at least established a line of communication between Lindsey Graham and me, and I'm sure that was not the most enjoyable chore that she had," McCain told Reuters.
Rice, however, is not necessarily adopting the senators' demand for aggressive U.S. military action in Syria. Obama said on Wednesday any strike would be "tailored, limited" and aimed at deterring Syria from using chemical weapons in the future.
"I think she realizes that they have to respond, but I get the impression that she is certainly not convinced of mine and Senator Graham's views that this has to be a sustained effort in order to bring down Bashar al-Assad ultimately," said McCain.
Representative Eliot Engel, the top Democrat on the House Foreign Affairs Committee, said Rice "was magnificent" on Thursday's conference call.
While Rice has generally been an advocate for action in Syria, he said she did not make the case during the call. "She has generally been, but she didn't make the case this time about it one way or another," he said in an interview.
Representative Buck McKeon, Republican chairman of the House Armed Services Committee, was not so complimentary.
While calling Rice and the other top officials "professional," he said: "I would have liked to have seen the president conducting this (call). And it kind of hit me (as) kind of ironic that she was the one who was first sent out to all of the Sunday talk shows to talk about Benghazi."
Exactly what advice Rice is providing Obama, or how large a role she is playing in internal debates, is unclear. White House officials declined to comment on those matters.
Her views on the Syrian conflict have basically mirrored the president's cautious approach of avoiding getting the United States bogged down in another costly war. Obama has withdrawn U.S. troops from Iraq and is winding down the combat mission in Afghanistan.
"I think the loss of human life really weighs on her, as it does on the president, and I think for all of us there is a desire to do something," said Democratic Representative Adam Schiff, who knows Rice. "But she is pragmatic enough to know what we do has to be carefully thought out, or it could have dramatically adverse consequences."
Rice has been active in U.S. efforts to assemble something resembling a coalition of like-minded nations to respond to what U.S. officials say is undeniable proof that the Syrian government of Assad used chemical weapons to kill hundreds in a Damascus suburb on August 21. That effort suffered a big setback on Thursday as close ally Britain said it would not participate in any military action.
Like Obama, she had long appeared reluctant for the United States to intervene militarily in Syria, fearing it was too risky. That position contrasted with her push for swift U.S. intervention in Libya in 2011, when, as U.S. ambassador to the United Nations, she urged skeptics at the Pentagon that it was worth supporting British and French calls for quick U.N.-backed action to halt Muammar Gaddafi's attacks on civilians.
Supporters of the Syrian rebels in Washington have their hopes pinned on Rice, because she sought U.N. sanctions against Assad's government and has been known at as a voice for protecting civilians endangered by conflict. Over 100,000 people have died in Syria since the uprising began there in March 2011.
"I think Susan Rice is someone who is more of an advocate of greater (U.S.) leadership and action on Syria," said Mouaz Moustafa, executive director of the Syrian Emergency Task Force, which supports humanitarian aid organizations in Syria.
LEAVING BENGHAZI BEHIND?
Rice has kept a low public profile at the White House, perhaps to some degree an effort to adjust to her new position and put behind her the controversy surrounding her after four Americans, including U.S. Ambassador Chris Stevens, were killed on September 11, 2012, in Benghazi.
The Obama administration's position on what happened in Benghazi, outlined in talking points that Rice stubbornly hewed to in five TV appearances the Sunday after the attack, was that the incident was a spontaneous demonstration in response to an anti-Muslim video. Ultimately, Islamist radicals were blamed for the attack.
Rice insisted she had no role in developing the Benghazi talking points.
She has clearly moved on. Since relocating to the White House, she has been immersed in crises ranging from the Egyptian military's ouster of elected President Mohamed Mursi and Russia's decision to grant asylum to an American accused of U.S. espionage charges to now, Syria.
The national security adviser is responsible for coordinating U.S. foreign policy and national security agencies for the president; developing options for action and offering personal advice; and in some White Houses - although not Obama's - acting as a public spokesperson for U.S. policies.
White House officials and friends say Rice enjoys the president's confidence and has adopted some subtle changes from the way her predecessor, Tom Donilon, operated. She has begun tweeting U.S. policy positions, something Donilon did not do.
"Met with a group of senior Israeli officials yesterday, including NSA Amidror, to discuss a range of issues, including Iran, Egypt, and Syria," she tweeted on Tuesday, referring to a group that included Israeli national security adviser Yaakov Amidror.
She attends a 7:45 a.m. meeting of senior White House staff each day where top aides lay out what they have on their plates. Donilon sent his deputy to that meeting.
Still, there have been no major departures from the structure established by Donilon, who was considered an inclusive, honest broker at his job and well-respected by Obama.
David Rothkopf, the chief executive and editor-in-chief of Foreign Policy magazine, who has known Rice since they worked together in former President Bill Clinton's administration, said Rice had put a focus on continuity and maintaining the approaches that had been developed over the preceding four years.
"She hasn't brought in a big team, she hasn't disrupted the staff structure there in a dramatic way. That tells a lot, not only about her, but how the president viewed the process that was developed under Donilon,"' he said.
(Additional reporting by Patricia Zengerle, Alex Dobuzinskis in California and by Lou Charbonneau at the United Nations; Editing by Warren Strobel and Peter Cooney)