Following Chuck Hagel’s surprise resignation on November 24th, and after several high profile candidates asked to be removed from consideration; President Obama nominated Ashton Carter to be the twenty-fifth secretary of defense. After a brief delay for back surgery, Carter will appear on Capitol Hill today for his confirmation hearing with the Senate Armed Services Committee — a confirmation he is expected to breeze through. A former deputy secretary of defense and chief Pentagon weapons buyer under Obama, and having served at the Department of Defense during the Clinton administration, Carter has apparently coveted the top job for some time. But what will he do now that he has it?

Carter’s background is different from most cabinet secretaries. He possesses bachelor’s degrees in physics and medieval history, and was a Rhodes Scholar at Oxford University — where he received doctorate in theoretical physics. Carter is mostly a technocrat though, with abundant experience in dealing with — and fighting within — the Pentagon’s mammoth bureaucracy.

An expert on nuclear weapons, Carter argued in the early days of the Clinton administration that the country could move to a nuclear force structure based solely on submarines. This submarine monad would have required the Air Force to give up its nuclear delivery platforms—nuclear-armed bombers and intercontinental ballistic missiles—and the air service did not take kindly to the suggestion. Carter’s subsequent ordeal fighting the USAF and its lobbying arm suggests an ability to wrangle with the military services and survive to tell the tale, even as losing the battle left the United States with an outdated nuclear force posture.

It is also in regard to nuclear weapons that Carter’s hawkish side emerges. In 2006, he famously co-authored an opinion piece for the Washington Post recommending strikes on North Korea to prevent the hermit kingdom from testing a long-range ballistic missile. While he has expressed concerns about Iran’s program as well, he does not seem to be an inveterate hawk determined to take preventive military action against potential proliferators. Moreover, Carter is likely to have little influence over any decision to follow the course of action he recommended almost a decade ago. The Obama administration has centralized foreign policy decision-making within the White House, with National Security Advisor Susan Rice and Chief of Staff Denis McDonough exerting the most influence. It is possible that Carter penetrates that bubble, but given past practice — and the fact that Carter will be the fourth person to hold his position during Obama’s tenure — that seems unlikely.

The new secretary of defense, as was the case with his predecessors, is also an avowed opponent of the budget caps instituted by the 2011 Budget Control Act. Of course, here too Carter is likely to face significant constraints. Despite the Pentagon consistently hitting the panic button, Congress shows little inclination to repeal the deficit reduction measure. Moreover, Obama has promised to veto any repeal legislation that does not include new revenues.

So what can the new secretary of defense actually accomplish?

Citing Charles Stevenson’s bookSECDEF, Fred Kaplan lays out the four jobs Carter will juggle in his new position: presidential advisor, war planner, diplomat, and manager of the Department of Defense.  As Kaplan argues, it is in the latter where Carter’s best chance for success lies. In particular, the new secretary of defense can help fix the Pentagon’s broken acquisition system. As its former chief of acquisition, Carter is well positioned to address the antiquated system that routinely wastes taxpayer money on unneeded programs and massive cost overruns on needed programs.

On that front, he will have allies in Congress. Both John McCain and Mac Thornberry, the incoming chairs of the Senate and House Armed Services Committees, see acquisition reform as one of their top priorities. Reforming acquisition will need a herculean effort though, even with the committee chairs supporting the effort. Carter knows the Pentagon well. He could be a very capable manager of the Building if he chooses to put his energies there instead of wasting political capital on a quixotic effort to repeal the Budget Control Act.