Hagel would be President Obama’s third secretary of Defense, and — if nominated — his second Republican cabinet member. Hagel, who initially supported President Obama in the 2008 election, has the moderate stance, bipartisan appeal, and political tact that the president is looking for.

In discussions with insiders, many think Hagel could (and would) follow the model of a recent predecessor: Robert Gates. Also a Republican, Gates served as President George W. Bush’s last secretary of Defense (as well as staying on as Obama’s first).

Gates, according to many experts, played his cards right as secretary of Defense. As he managed two wars in two countries, Gates built consensus within government and out of the media spotlight.

Instead of going public — “and beating his chest like Rumsfeld did,” said one insider — Gates quietly shaped the Pentagon from within. A career government official, he understood that inter-agency jiu-jitsu and the craft of behind-closed-doors negotiations were essential parts of the job.

In other words, Gates understood the importance of relationships. He quietly formed the Pentagon into a place that allowed diverse intellects to participate in the decision-making process. He served as an effective interlocutor between the triangle of powers that run America’s national defense — the Pentagon, the White House and Congress.

And Gates, like his successor Leon Panetta, cared about his staff’s talent, not party affiliation. He carried much of the same Pentagon personnel into for the Obama Administration, demonstrating his appreciation of continuity and institutional know-how at the Department of Defense.

Gates’ performance can be boiled down to an important lesson: diplomacy can be used not just between countries, but inside Washington, too.
The next secretary of Defense will need to preserve the Pentagon’s identity as a practical, no-nonsense, forward-thinking organization. Just as crucial, the next Secretary will have to work with Congress amid difficult budget cuts, and with the White House to confront new threats.

Hagel, a former Senator and Army veteran, is well-suited to tackle the job. By tapping into his deep ties to Congress, he could convince former colleagues on the Hill to fund new strategic initiatives. And, given his close relationship with the President, Hagel could work efficiently with the White House to rapidly respond to emergent threats.

With that in mind, the list of priorities for the next secretary of Defense — whoever it may be — is immense:

• Executing the “Pacific Pivot”: With the war in Afghanistan winding down, the military will shift to a greater focus on the Asia-Pacific region. In the last year, the U.S. has put Marines in Australia, sailed ships into the South China Sea, and invested in regional partners like Taiwan and Burma. Facing budget cuts, the next secretary will have to discern how the U.S. will continue to advance this strategy successfully.

• Preparing for cyberwar: With more than 40,000 cyber attacks against the Department of Defense every day, cybersecurity is expected to be one of the few areas of the defense budget getting increased funding. Panetta’s successor will have to find solutions to a rapidly-changing, flexible and fickle threat.

• Transforming the military into a 21st-century force: New battlefields — in space, on the web and in the air — combined with a military exhausted from ten years of war, means the Pentagon will have to do more with less. The next secretary must address how the U.S. can slim down its force, stay ahead of its enemies, and still invest in promising technologies with fewer resources.

• Dealing with Iran and Syria, without boots on the ground: The American public has little appetite for a military confrontation in either country. Obama’s third secretary of Defense will have to continue to embrace diplomacy as a national security strategy. Gates and Panetta have championed this approach already, but it can be deepened. By using aid, sanctions, and other non-violent—yet potent—forms of geopolitical influence, the Pentagon will have to find creative solutions to complex (and dangerous) situations.  

• And, most critically, reforming the defense budget: If sequestration occurs, the Department of Defense will face an additional $500 billion in cuts — what Secretary Panetta has called “the meat ax approach.” With $487 billion in cuts already scheduled over the next decade, sequestration will undoubtedly have an impact on defense capabilities. No matter what happens, the next Secretary must slim down the Pentagon’s balance sheet, while keeping an eye on emergent threats and drawing down responsibly in Afghanistan.

Though Hagel is widely regarded to be the frontrunner, other qualified candidates are waiting in the wings. Should the Senate confirmation hearings get testy for Hagel, there are three other qualified candidates on the short list:

Michele Flournoy: “[She has] a black belt in the Pentagon,” said one expert—and credentials, too. Flournoy, the former director of Policy Planning for the Department of Defense, has a reputation for knowing the issues as well as anyone. She’s also the co-founder of the Center for New American Security, a leading national security think-tank. Flournoy, a Democrat who worked in the Pentagon during the Clinton Administration, would also be the first woman Secretary of Defense.

Dr. Ashton Carter: With a Ph.D. in Theoretical Physics, eleven books to his name and experience as the chairman of the International and Global Affairs faculty at Harvard University’s Kennedy School of Government, Carter is well-qualified to lead the Pentagon. If nominated, his transition to the top job would be seamless: he is currently the Deputy Secretary of Defense. Carter has earned a reputation for being able to cut costs by streamlining weapons purchases. With the defense budget facing significant cuts (whether or not sequestration goes through), Carter’s cost-conscious and pragmatic stance makes him a viable candidate for the job.

Dr. Richard Danzig: While not as frequently mentioned in the media as Flournoy and Carter, Danzig has dark-horse appeal. Having served as a senior advisor on national security issues for then-candidate Obama in 2008, Danzig has a close relationship with The White House. He also served as secretary of the Navy during both the Clinton and George W. Bush administrations. Like Carter, Danzig is a Rhodes Scholar and Oxford Ph.D. — and, like Flournoy, he now works at the Center for New American Security.

At the end of the day, all are exceptional leaders with impeccable qualifications.

For Carter and Flournoy, detail-oriented attitudes and policy experience make them viable choices. Both have been deeply involved in the Department of Defense — and the big issues — for years, so they have in-the-trenches, gritty understanding of how the Pentagon works. As one insider said, “They are quintessential pentagon civilians.”

On the issues, there are few picks with better credentials. With defense budget cuts poised to be a divisive and sensitive issue going into 2013, Carter and Flournoy — and Danzig, as well—are well prepared to handle the storm. They would be able to address defense spending from a position of understanding, pragmatism and strategy.

Yet, Hagel is the leading pick for the post, particularly because of his political skill and appeal. His Senate experience would enable him to negotiate with Congress effectively. Indeed, as one expert said, “Presidents, in the past, have reached to the Hill for Secretary of Defense. They feel like in order to make cuts, it gets political, and you need someone to manage that. [The defense budget] is so at the mercy of Congress that you need someone to manage that process.”

No matter who is selected, he or she will have the opportunity to guide the Department of Defense through a historic period of change. Between winding down a war, bringing troops home, confronting new threats, streamlining the military and responsibly cutting hundreds of billions from the Pentagon’s balance sheet — all while keeping Americans safe—the next Secretary will be assured of one thing: a lack of sleep.

Gaynor serves as the digital strategist and writer at the Truman National Security Project in Washington, D.C.