WASHINGTON (AP) - The nomination of policy wonk Ashton Carter to lead the Defense Department marks the most significant change to President Barack Obama's beleaguered national security team in nearly two years. But there is little indication the shake-up portends a broader shift in administration policy - nor is it clear that Carter can break into the president's tight inner circle.
Obama announced Carter's nomination at the White House Friday, praising the Pentagon veteran as an innovator and reformer who can quickly step back into an administration grappling with security challenges in the Mideast, Eastern Europe and elsewhere.
"When we talked about this job, we talked about how we're going to have to make smart choices precisely because there are so many challenges out there," Obama said.
The nomination of Carter, a physicist who has served two Democratic presidents at the Pentagon, was welcomed by some Republicans as well as Democrats, and he is expected to be easily confirmed by the new GOP-controlled Senate. Still, Republicans are eager to use his hearings as a new chance to challenge Obama.
"Ashton Carter has the knowledge and capability to serve as secretary of defense during these difficult times," said Sen. Lindsey Graham, R-S.C. "I expect he will face tough questions at his confirmation hearing about President Obama's failing national security policy, but I expect he will be confirmed."
Carter would replace Chuck Hagel, who resigned last week under pressure from Obama. Hagel had been scheduled to attend Carter's nomination ceremony, but abruptly backed out Friday morning. The Pentagon said the two men did speak by phone.
Administration officials say Obama decided to make a change at the Pentagon after determining Hagel, the Republican former Nebraska senator, wasn't up to the job of managing a burgeoning military campaign against Islamic State militants in Iraq and Syria. The military is also increasing its presence in Eastern Europe, aimed at deterring Russian aggression, all while grappling with deep budget cuts.
Carter, who has held numerous high-level jobs at the Pentagon under Obama and in the Clinton administration, ended his most recent tenure at the department in late 2013, before the Islamic State became a top U.S. priority and before Russian President Vladimir Putin began maneuvering in Ukraine. Carter offered no insight Friday into how he viewed the current U.S. response to those efforts.
"The world has changed since he departed," said Julianne Smith, a former White House national security official who worked closely with Carter during Obama's first term. She said he appears to share Obama's preference for taking military action alongside international partners, as in the current campaign against the Islamic State.
"He is not someone I get the sense who would want to see the U.S. pursue something unilateral unless direct U.S. interests were at stake," added Smith, a senior fellow at the Center for a New American Security.
Carter will take over a Pentagon facing congressionally mandated budget cuts that have left some concerned about putting the military on weak footing. Jeremy Bash, a former Pentagon chief of staff who is assisting Carter with the nomination process, said Carter's primary focus would be on balancing a need to combat global threats with trimming the department's budget.
"Ash is going to have to focus on the question of risk," Bash said. "As we downsize, where are the areas where we can we afford risk?"
If confirmed, Carter will become Obama's fourth defense secretary. The president's relationship with the Pentagon has often been strained, with some officials in the department saying Obama views the military skeptically and centralizes decision making in the West Wing.
Two of Obama's previous Pentagon chiefs, Robert Gates and Leon Panetta, have publicly aired their grievances with what they saw as White House micromanagement. Both have spoken with Carter in recent days.
Hagel was tapped for the Pentagon post in part because he was seen as someone who would largely acquiesce to the White House, though he, too, is said to have grown frustrated, particularly with the policymaking process overseen by National Security Adviser Susan Rice.
Despite persistent criticism of his foreign policy and decision making, Obama appears unlikely to oust Rice or other members of the White House national security team.
In brief remarks Friday, Carter pledged to give the president "candid military advice" - a statement seen by some as an attempt to reassure those in the Pentagon who felt Hagel had little influence.
People close to Carter say he has one advantage: a good relationship with Rice, whom he has known for many years. The two embraced warmly following Friday's White House ceremony.
Carter will assume the top job with plenty of insight into the dynamic between the Pentagon and the White House. He held the No. 2 job at the Pentagon from October 2011 to December 2013 and also served as the Defense Department's technology and weapons-buying chief during the opening years of Obama's presidency.